Note that the only difference between String Transformation 1 and String Transformation 2 is in the move Koa does. In this version the letter y Koa selects must be strictly greater alphabetically than x (read statement for better understanding). You can make hacks in these problems independently.

Koa the Koala has two strings A and B of the same length n (|A|=|B|=n) consisting of the first 20 lowercase English alphabet letters (ie. from a to t).

In one move Koa:

  1. selects some subset of positions p_1, p_2, …, p_k (k ≥ 1; 1 ≤ p_i ≤ n; p_i ≠ p_j if i ≠ j) of A such that A_{p_1} = A_{p_2} = … = A_{p_k} = x (ie. all letters on this positions are equal to some letter x).

  2. selects a letter y (from the first 20 lowercase letters in English alphabet) such that y>x (ie. letter y is strictly greater alphabetically than x).

  3. sets each letter in positions p_1, p_2, …, p_k to letter y. More formally: for each i (1 ≤ i ≤ k) Koa sets A_{p_i} = y.

Note that you can only modify letters in string A.




Koa wants to know the smallest number of moves she has to do to make strings equal to each other (A = B) or to determine that there is no way to make them equal. Help her!

Input

Each test contains multiple test cases. The first line contains t (1 ≤ t ≤ 10) — the number of test cases. Description of the test cases follows.

The first line of each test case contains one integer n (1 ≤ n ≤ 10^5) — the length of strings A and B.

The second line of each test case contains string A (|A|=n).

The third line of each test case contains string B (|B|=n).

Both strings consists of the first 20 lowercase English alphabet letters (ie. from a to t).

It is guaranteed that the sum of n over all test cases does not exceed 10^5.

Output

For each test case:

Print on a single line the smallest number of moves she has to do to make strings equal to each other (A = B) or -1 if there is no way to make them equal.

Example

Input


5
3
aab
bcc
4
cabc
abcb
3
abc
tsr
4
aabd
cccd
5
abcbd
bcdda


Output


2
-1
3
2
-1

Note

  * In the 1-st test case Koa: 
    1. selects positions 1 and 2 and sets A_1 = A_2 =  b (\color{red}{aa}b → \color{blue}{bb}b). 
    2. selects positions 2 and 3 and sets A_2 = A_3 =  c (b\color{red}{bb} → b\color{blue}{cc}). 

  * In the 2-nd test case Koa has no way to make string A equal B.

  * In the 3-rd test case Koa: 
    1. selects position 1 and sets A_1 =  t (\color{red}{a}bc → \color{blue}{t}bc). 
    2. selects position 2 and sets A_2 =  s (t\color{red}{b}c → t\color{blue}{s}c). 
    3. selects position 3 and sets A_3 =  r (ts\color{red}{c} → ts\color{blue}{r}). 
import java.io.*;
import java.util.*;


public class Main {
	static void solve() {
		int tests = ni();
		for(int test = 0; test<tests; test++)testCase();
	}	
	static void testCase() {
		int n = ni();
		char[] s = ns(n), t = ns(n);
		for(int i=0;i<n;i++) {
			if(s[i] > t[i]) {
				out.println(-1);
				return;
			}
		}
		
		Set<Character> preSet[] = new HashSet[26];
		for(int i=0;i<26;i++)preSet[i] = new HashSet<>();
		for(int i=0;i<n;i++) {
			if(s[i] == t[i])continue;
			preSet[s[i] - 'a'].add(t[i]);
		}
		
		Set<Character>[] set = new HashSet[26];
		for(int i=0;i<26;i++)set[i] = new HashSet<>();
		for(int i=0;i<26;i++) {
			for(char c : preSet[i]) {
				boolean containedBefore = false;
				for(int j=0;j<i;j++) {
					if(set[j].contains((char)(i+'a'))) {
						set[j].add(c);
						containedBefore = true;
						break;
					}
				}
				if(containedBefore)continue;
				set[i].add(c);
			}
		}
		
		int containedFirst[] = new int[26];
		fill(containedFirst, -1);
		for(int i=0;i<26;i++) {
			for(char c : set[i]) {
				int now = c - 'a';
				if(containedFirst[now] != -1)continue;
				containedFirst[now] = i;
			}
		}
		
		for(int i=0;i<26;i++) {
			int youngest = inf;
			for(char c : set[i]) {
				int now = c - 'a';
				youngest = min(youngest, containedFirst[now]);
			}
			if(youngest == inf)continue;
			if(i == youngest) continue; 
			set[youngest].add((char)(i + 'a'));
			set[youngest].addAll(set[i]);
			set[i].clear();
			for(int j=0;j<26;j++) {
				if(containedFirst[j]==i) {
					containedFirst[j] = youngest;
				}
			}
		}
		
		int ans = 0;
		for(int i=0;i<26;i++) {
			ans += set[i].size();
		}
		out.println(ans);
	}
	
	//constants
	static final int inf = Integer.MAX_VALUE / 2;
	static final long linf = Long.MAX_VALUE / 3;
	static final double dinf = Double.MAX_VALUE / 3;
	static final long mod = (long) 1e9 + 7;
	static final int[] dx = { -1, 0, 1, 0 }, dy = { 0, -1, 0, 1 }, dx8 = { -1, -1, -1, 0, 0, 1, 1, 1 }, dy8 = { -1, 0, 1, -1, 1, -1, 0, 1 };
	static final double eps = 1e-10, pi = Math.PI;
	static StringBuilder sb = new StringBuilder();
	
	//libraries
	static void printAll(int[] a) {
		Arrays.stream(a).forEach(i->out.print(i + " "));
		out.println();
	}
	static void printAll(long[] a) {
		Arrays.stream(a).forEach(i->out.print(i + " "));
		out.println();
	}
	static void printAll(int[] a, int add) {
		Arrays.stream(a).forEach(i->out.print(i + add + " "));
		out.println();
	}
	static void printAll(long[] a, long add) {
		Arrays.stream(a).forEach(i->out.print(i + add + " "));
		out.println();
	}
	static List<Integer>[] makeTree(List<Integer>[] graph, int vertexNum, int edgeNum) {
		graph = new ArrayList[vertexNum];
		for(int i=0;i<vertexNum;i++)graph[i] = new ArrayList<>();
		for(int i=0;i<edgeNum;i++) {
			int u = ni()-1, v = ni()-1;
			graph[u].add(v);
			graph[v].add(u);
		}
		return graph;
	}
	static long[] cum(int a[]) {
		long[] cum = new long[a.length + 1];
		for(int i=0;i<a.length;i++) cum[i+1] = cum[i] + a[i];
		return cum;
	}
	static long[] cum(long a[]) {
		long[] cum = new long[a.length + 1];
		for(int i=0;i<a.length;i++) cum[i+1] = cum[i] + a[i];
		return cum;
	}
	static long sum(int a[]) {
		long res = 0;
		for(int i=0;i<a.length;i++) res += a[i];
		return res;
	}
	static long sum(long a[]) {
		long res = 0;
		for(int i=0;i<a.length;i++) res += a[i];
		return res;
	}
	static void reverse(int ar[]) {
		int len = ar.length;
		for (int i = 0; i < len / 2; i++) {
			int t = ar[i];
			ar[i] = ar[len - 1 - i];
			ar[len - 1 - i] = t;
		}
	}
	static void reverse(long ar[]) {
		int len = ar.length;
		for (int i = 0; i < len / 2; i++) {
			long t = ar[i];
			ar[i] = ar[len - 1 - i];
			ar[len - 1 - i] = t;
		}
	}
	static void reverse(double ar[]) {
		int len = ar.length;
		for (int i = 0; i < len / 2; i++) {
			double t = ar[i];
			ar[i] = ar[len - 1 - i];
			ar[len - 1 - i] = t;
		}
	}
	static void reverse(char ar[]) {
		int len = ar.length;
		for (int i = 0; i < len / 2; i++) {
			char t = ar[i];
			ar[i] = ar[len - 1 - i];
			ar[len - 1 - i] = t;
		}
	}
	static String getReverse(String s) {
		char c[] = s.toCharArray();
		reverse(c);
		s = String.valueOf(c);
		return s;
	}
	static <T> void reverse(List<T> ls) {
		int sz = ls.size();
		for (int i = 0; i < sz / 2; i++) {
			T t = ls.get(i);
			ls.set(i, ls.get(sz - 1 - i));
			ls.set(sz - 1 - i, t);
		}
	}
	static <T> void reverse(T[] ar) {
		int len = ar.length;
		for (int i = 0; i < len / 2; i++) {
			T t = ar[i];
			ar[i] = ar[len - 1 - i];
			ar[len - 1 - i] = t;
		}
	}
	static void sbnl() {//StringBuilderに改行文字をappendする
		sb.append("\n");
	}
	static int lowerBound(int[] a, int x) {
		int l = -1, r = a.length;
		while (r - l > 1) {
			int c = (l + r) / 2;
			if (a[c] < x) {
				l = c;
			} else {
				r = c;
			}
		}
		return r;
	}
	static int upperBound(int[] a, int x) {
		int l = -1, r = a.length;
		while (r - l > 1) {
			int c = (l + r) / 2;
			if (a[c] <= x) {
				l = c;
			} else {
				r = c;
			}
		}
		return r;
	}
	static int rlowerBound(int[] a, int x) {
		int l = -1, r = a.length;
		while (r - l > 1) {
			int c = (l + r) / 2;
			if (a[c] > x) {
				l = c;
			} else {
				r = c;
			}
		}
		return r;
	}
	static int rupperBound(int[] a, int x) {
		int l = -1, r = a.length;
		while (r - l > 1) {
			int c = (l + r) / 2;
			if (a[c] >= x) {
				l = c;
			} else {
				r = c;
			}
		}
		return r;
	}
	static int lowerBound(long[] a, long x) {
		int l = -1, r = a.length;
		while (r - l > 1) {
			int c = (l + r) / 2;
			if (a[c] < x) {
				l = c;
			} else {
				r = c;
			}
		}
		return r;
	}
	static int upperBound(long[] a, long x) {
		int l = -1, r = a.length;
		while (r - l > 1) {
			int c = (l + r) / 2;
			if (a[c] <= x) {
				l = c;
			} else {
				r = c;
			}
		}
		return r;
	}
	static int rlowerBound(long[] a, long x) {
		int l = -1, r = a.length;
		while (r - l > 1) {
			int c = (l + r) / 2;
			if (a[c] > x) {
				l = c;
			} else {
				r = c;
			}
		}
		return r;
	}
	static int rupperBound(long[] a, long x) {
		int l = -1, r = a.length;
		while (r - l > 1) {
			int c = (l + r) / 2;
			if (a[c] >= x) {
				l = c;
			} else {
				r = c;
			}
		}
		return r;
	}
	static int lowerBound(double[] a, double x) {
		int l = -1, r = a.length;
		while (r - l > 1) {
			int c = (l + r) / 2;
			if (a[c] < x) {
				l = c;
			} else {
				r = c;
			}
		}
		return r;
	}
	static int upperBound(double[] a, double x) {
		int l = -1, r = a.length;
		while (r - l > 1) {
			int c = (l + r) / 2;
			if (a[c] <= x) {
				l = c;
			} else {
				r = c;
			}
		}
		return r;
	}
	static int rlowerBound(double[] a, double x) {
		int l = -1, r = a.length;
		while (r - l > 1) {
			int c = (l + r) / 2;
			if (a[c] > x) {
				l = c;
			} else {
				r = c;
			}
		}
		return r;
	}
	static int rupperBound(double[] a, double x) {
		int l = -1, r = a.length;
		while (r - l > 1) {
			int c = (l + r) / 2;
			if (a[c] >= x) {
				l = c;
			} else {
				r = c;
			}
		}
		return r;
	}
	static int lowerBound(char[] a, char x) {
		int l = -1, r = a.length;
		while (r - l > 1) {
			int c = (l + r) / 2;
			if (a[c] < x) {
				l = c;
			} else {
				r = c;
			}
		}
		return r;
	}
	static int upperBound(char[] a, char x) {
		int l = -1, r = a.length;
		while (r - l > 1) {
			int c = (l + r) / 2;
			if (a[c] <= x) {
				l = c;
			} else {
				r = c;
			}
		}
		return r;
	}
	static int rlowerBound(char[] a, char x) {
		int l = -1, r = a.length;
		while (r - l > 1) {
			int c = (l + r) / 2;
			if (a[c] > x) {
				l = c;
			} else {
				r = c;
			}
		}
		return r;
	}
	static int rupperBound(char[] a, char x) {
		int l = -1, r = a.length;
		while (r - l > 1) {
			int c = (l + r) / 2;
			if (a[c] >= x) {
				l = c;
			} else {
				r = c;
			}
		}
		return r;
	}
	static <T> int lowerBound(List<T> ls, T x) throws RuntimeException {
		if (ls.size() == 0)
			return -1;
		if (ls.get(0) instanceof Integer) {
			return ~Collections.binarySearch(ls, x, (t1, t2) -> ((Integer) t1).compareTo((Integer) t2) >= 0 ? 1 : -1);
		} else if (ls.get(0) instanceof Long) {
			return ~Collections.binarySearch(ls, x, (t1, t2) -> ((Long) t1).compareTo((Long) t2) >= 0 ? 1 : -1);
		} else if (ls.get(0) instanceof Double) {
			return ~Collections.binarySearch(ls, x, (t1, t2) -> ((Double) t1).compareTo((Double) t2) >= 0 ? 1 : -1);
		} else {
			System.err.println(
					String.format("%s:数値でないリストを二分探索しています。", Thread.currentThread().getStackTrace()[1].getMethodName()));
			throw new RuntimeException();
		}
	}
	static <T> int upperBound(List<T> ls, T x) throws RuntimeException {
		if (ls.size() == 0)
			return -1;
		if (ls.get(0) instanceof Integer) {
			return ~Collections.binarySearch(ls, x, (t1, t2) -> ((Integer) t1).compareTo((Integer) t2) > 0 ? 1 : -1);
		} else if (ls.get(0) instanceof Long) {
			return ~Collections.binarySearch(ls, x, (t1, t2) -> ((Long) t1).compareTo((Long) t2) > 0 ? 1 : -1);
		} else if (ls.get(0) instanceof Double) {
			return ~Collections.binarySearch(ls, x, (t1, t2) -> ((Double) t1).compareTo((Double) t2) > 0 ? 1 : -1);
		} else {
			System.err.println(
					String.format("%s:数値でないリストを二分探索しています。", Thread.currentThread().getStackTrace()[1].getMethodName()));
			throw new RuntimeException();
		}
	}
	static <T> int rupperBound(List<T> ls, T x) throws RuntimeException {
		if (ls.size() == 0)
			return -1;
		if (ls.get(0) instanceof Integer) {
			return ~Collections.binarySearch(ls, x, (t1, t2) -> ((Integer) t1).compareTo((Integer) t2) < 0 ? 1 : -1);
		} else if (ls.get(0) instanceof Long) {
			return ~Collections.binarySearch(ls, x, (t1, t2) -> ((Long) t1).compareTo((Long) t2) < 0 ? 1 : -1);
		} else if (ls.get(0) instanceof Double) {
			return ~Collections.binarySearch(ls, x, (t1, t2) -> ((Double) t1).compareTo((Double) t2) < 0 ? 1 : -1);
		} else {
			System.err.println(
					String.format("%s:数値でないリストを二分探索しています。", Thread.currentThread().getStackTrace()[1].getMethodName()));
			throw new RuntimeException();
		}
	}
	static <T> int rlowerBound(List<T> ls, T x) {
		if (ls.size() == 0)
			return -1;
		if (ls.get(0) instanceof Integer) {
			return ~Collections.binarySearch(ls, x, (t1, t2) -> ((Integer) t1).compareTo((Integer) t2) <= 0 ? 1 : -1);
		} else if (ls.get(0) instanceof Long) {
			return ~Collections.binarySearch(ls, x, (t1, t2) -> ((Long) t1).compareTo((Long) t2) <= 0 ? 1 : -1);
		} else if (ls.get(0) instanceof Double) {
			return ~Collections.binarySearch(ls, x, (t1, t2) -> ((Double) t1).compareTo((Double) t2) <= 0 ? 1 : -1);
		} else {
			System.err.println(
					String.format("%s:数値でないリストを二分探索しています。", Thread.currentThread().getStackTrace()[1].getMethodName()));
			throw new RuntimeException();
		}
	}
	static int[] concat(int x, int arr[]) {
		int ret[] = new int[arr.length + 1];
		System.arraycopy(arr, 0, ret, 1, ret.length - 1);
		ret[0] = x;
		return ret;
	}
	static int[] concat(int arr[], int x) {
		int ret[] = new int[arr.length + 1];
		System.arraycopy(arr, 0, ret, 0, ret.length - 1);
		ret[ret.length - 1] = x;
		return ret;
	}
	static long[] concat(long x, long arr[]) {
		long ret[] = new long[arr.length + 1];
		System.arraycopy(arr, 0, ret, 1, ret.length - 1);
		ret[0] = x;
		return ret;
	}
	static long[] concat(long arr[], long x) {
		long ret[] = new long[arr.length + 1];
		System.arraycopy(arr, 0, ret, 0, ret.length - 1);
		ret[ret.length - 1] = x;
		return ret;
	}
	static char[] concat(char x, char arr[]) {
		char ret[] = new char[arr.length + 1];
		System.arraycopy(arr, 0, ret, 0, ret.length - 1);
		ret[ret.length - 1] = x;
		return ret;
	}
	static char[] concat(char arr[], char x) {
		char ret[] = new char[arr.length + 1];
		System.arraycopy(arr, 0, ret, 0, ret.length - 1);
		ret[ret.length - 1] = x;
		return ret;
	}
	static int max(int x, int y) {
		return Math.max(x, y);
	}
	static int min(int x, int y) {
		return Math.min(x, y);
	}
	static int max(int x, int y, int z) {
		x = Math.max(x, y);
		x = Math.max(x, z);
		return x;
	}
	static int min(int x, int y, int z) {
		x = Math.min(x, y);
		x = Math.min(x, z);
		return x;
	}
	static long max(long x, long y) {
		return Math.max(x, y);
	}
	static long min(long x, long y) {
		return Math.min(x, y);
	}
	static long max(long x, long y, long z) {
		x = Math.max(x, y);
		x = Math.max(x, z);
		return x;
	}
	static long min(long x, long y, long z) {
		x = Math.min(x, y);
		x = Math.min(x, z);
		return x;
	}
	static double max(double x, double y) {
		return Math.max(x, y);
	}
	static double min(double x, double y) {
		return Math.min(x, y);
	}
	static double max(double x, double y, double z) {
		x = Math.max(x, y);
		x = Math.max(x, z);
		return x;
	}
	static double min(double x, double y, double z) {
		x = Math.min(x, y);
		x = Math.min(x, z);
		return x;
	}
	static void sort(int[] ar) {
		Arrays.sort(ar);
	}
	static void sort(long[] ar) {
		Arrays.sort(ar);
	}
	static void sort(double[] ar) {
		Arrays.sort(ar);
	}
	static void sort(char[] ar) {
		Arrays.sort(ar);
	}
	static void rsort(int[] ar) {
		Arrays.sort(ar);
		int len = ar.length;
		for (int i = 0; i < len / 2; i++) {
			int tmp = ar[i];
			ar[i] = ar[len - 1 - i];
			ar[len - 1 - i] = tmp;
		}
	}
	static void rsort(long[] ar) {
		Arrays.sort(ar);
		int len = ar.length;
		for (int i = 0; i < len / 2; i++) {
			long tmp = ar[i];
			ar[i] = ar[len - 1 - i];
			ar[len - 1 - i] = tmp;
		}
	}
	static void rsort(double[] ar) {
		Arrays.sort(ar);
		int len = ar.length;
		for (int i = 0; i < len / 2; i++) {
			double tmp = ar[i];
			ar[i] = ar[len - 1 - i];
			ar[len - 1 - i] = tmp;
		}
	}
	static void rsort(char[] ar) {
		Arrays.sort(ar);
		int len = ar.length;
		for (int i = 0; i < len / 2; i++) {
			char tmp = ar[i];
			ar[i] = ar[len - 1 - i];
			ar[len - 1 - i] = tmp;
		}
	}
	static void fill(int arr[], int x) {
		Arrays.fill(arr, x);
	}
	static void fill(long arr[], long x) {
		Arrays.fill(arr, x);
	}
	static void fill(boolean arr[], boolean x) {
		Arrays.fill(arr, x);
	}
	static void fill(double arr[], double x) {
		Arrays.fill(arr, x);
	}
	static void fill(int arr[][], int x) {
		for (int i = 0; i < arr.length; i++)
			Arrays.fill(arr[i], x);
	}
	static void fill(long arr[][], long x) {
		for (int i = 0; i < arr.length; i++)
			Arrays.fill(arr[i], x);
	}
	static void fill(double arr[][], double x) {
		for (int i = 0; i < arr.length; i++)
			Arrays.fill(arr[i], x);
	}
	static void fill(boolean arr[][], boolean x) {
		for (int i = 0; i < arr.length; i++)
			Arrays.fill(arr[i], x);
	}
	//MOD culc
	static long plus(long x, long y) {
		long res = (x + y) % mod;
		return res < 0 ? res + mod : res;
	}
	static long sub(long x, long y) {
		long res = (x - y) % mod;
		return res < 0 ? res + mod : res;
	}
	static long mul(long x, long y) {
		long res = (x * y) % mod;
		return res < 0 ? res + mod : res;
	}
	static long div(long x, long y) {
		long res = x * pow(y, mod - 2) % mod;
		return res < 0 ? res + mod : res;
	}
	static long pow(long x, long y) {
		if (y < 0)
			return 0;
		if (y == 0)
			return 1;
		if (y % 2 == 1)
			return (x * pow(x, y - 1)) % mod;
		long root = pow(x, y / 2);
		return root * root % mod;
	}
	public static void main(String[] args) throws Exception {
		is = INPUT.isEmpty() ? System.in : new ByteArrayInputStream(INPUT.getBytes());
		out = new PrintWriter(System.out);
		solve();
		out.flush();
	}
	//input
	static InputStream is;
	static PrintWriter out;
	static String INPUT = "";
	private static byte[] inbuf = new byte[1024];
	static int lenbuf = 0, ptrbuf = 0;
	private static int readByte() {
		if (lenbuf == -1)
			throw new InputMismatchException();
		if (ptrbuf >= lenbuf) {
			ptrbuf = 0;
			try {
				lenbuf = is.read(inbuf);
			} catch (IOException e) {
				throw new InputMismatchException();
			}
			if (lenbuf <= 0)
				return -1;
		}
		return inbuf[ptrbuf++];
	}
	private static boolean isSpaceChar(int c) {
		return !(c >= 33 && c <= 126);
	}
	private static int skip() {
		int b;
		while ((b = readByte()) != -1 && isSpaceChar(b))
			;
		return b;
	}
	@SuppressWarnings("unused")
	private static double nd() {
		return Double.parseDouble(ns());
	}
	@SuppressWarnings("unused")
	private static char nc() {
		return (char) skip();
	}
	private static String ns() {
		int b = skip();
		StringBuilder sb = new StringBuilder();
		while (!(isSpaceChar(b))) {
			sb.appendCodePoint(b);
			b = readByte();
		}
		return sb.toString();
	}
	private static char[] ns(int n) {
		char[] buf = new char[n];
		int b = skip(), p = 0;
		while (p < n && !(isSpaceChar(b))) {
			buf[p++] = (char) b;
			b = readByte();
		}
		return n == p ? buf : Arrays.copyOf(buf, p);
	}
	@SuppressWarnings("unused")
	private static char[][] nm(int n, int m) {
		char[][] map = new char[n][];
		for (int i = 0; i < n; i++)
			map[i] = ns(m);
		return map;
	}
	@SuppressWarnings("unused")
	private static int[] na(int n) {
		int[] a = new int[n];
		for (int i = 0; i < n; i++)
			a[i] = ni();
		return a;
	}
	@SuppressWarnings("unused")
	private static long[] nla(int n) {
		long[] a = new long[n];
		for (int i = 0; i < n; i++)
			a[i] = nl();
		return a;
	}
	
	@SuppressWarnings("unused")
	private static int[][] nas(int n, int m){
		int[][] res = new int[n][m];
		for(int i=0;i<n;i++) {
			for(int j=0;j<m;j++) {
				res[i][j] = ni();
			}
		}
		return res;
	}
	
	@SuppressWarnings("unused")
	private static long[][] nlas(int n, int m){
		long[][] res = new long[n][m];
		for(int i=0;i<n;i++) {
			for(int j=0;j<m;j++) {
				res[i][j] = nl();
			}
		}
		return res;
	}
	
	@SuppressWarnings("unused")
	private static int ni() {
		int num = 0, b;
		boolean minus = false;
		while ((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'))
			;
		if (b == '-') {
			minus = true;
			b = readByte();
		}
		
		while (true) {
			if (b >= '0' && b <= '9') {
				num = num * 10 + (b - '0');
			} else {
				return minus ? -num : num;
			}
			b = readByte();
		}
	}
	@SuppressWarnings("unused")
	private static long nl() {
		long num = 0;
		int b;
		boolean minus = false;
		while ((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'))
			;
		if (b == '-') {
			minus = true;
			b = readByte();
		}
		
		while (true) {
			if (b >= '0' && b <= '9') {
				num = num * 10 + (b - '0');
			} else {
				return minus ? -num : num;
			}
			b = readByte();
		}
	}
}
