Some natural number was written on the board. Its sum of digits was not less than k. But you were distracted a bit, and someone changed this number to n, replacing some digits with others. It's known that the length of the number didn't change.

You have to find the minimum number of digits in which these two numbers can differ.

Input

The first line contains integer k (1 ≤ k ≤ 109).

The second line contains integer n (1 ≤ n < 10100000).

There are no leading zeros in n. It's guaranteed that this situation is possible.

Output

Print the minimum number of digits in which the initial number and n can differ.

Examples

Input

3
11


Output

1


Input

3
99


Output

0

Note

In the first example, the initial number could be 12.

In the second example the sum of the digits of n is not less than k. The initial number could be equal to n.
import java.io.*;
import java.util.*;
 
	 
	 
	public   class Main {
		private InputStream is;
		private PrintWriter out;
		int time = 0, val[][], DP[], start[], end[], dist[],  black[], MOD = (int)(1e9+7), arr[], weight[][], x[], y[], parent[];
		int MAX = 800000, N, K;
		long red[];
		ArrayList<Integer>[] amp;
		ArrayList<Pair>[][] pmp;
		boolean b[], boo[][];
		Pair prr[];
		HashMap<Integer,Long> hm[] = new HashMap[305];
		long Dp[][][][] = new long[110][110][12][12];
		void soln() {
			is = System.in;
			out = new PrintWriter(System.out);
			long s = System.currentTimeMillis();
			solve();
			//out.close();
			out.flush();
			//tr(System.currentTimeMillis() - s + "ms");
		}
		public static void main(String[] args) throws Exception {
			new Thread(null, new Runnable() {
			public void run() {
				try {
			//new CODEFORCES().soln();
			} catch (Exception e) {
					System.out.println(e);
				}
			}
		}, "1", 1 << 26).start();
			new Main().soln();
		}
		int ans = 0, cost = 0;
		char ch[], ch1[];
		int dp[][] = new int[5010][5010], n;
		void solve(){
			int k = ni();
			char ch[] = ns().toCharArray();
			Arrays.sort(ch);
			int n = ch.length;
			int sum = 0;
			for(char c:ch) sum += (c-'0');
			k -= sum;
			for(int i = 0; i<n;i++){
				if(k<=0){
					System.out.println(i);return;
				}
				k -= ('9'-ch[i]);
			}
			if(k<=0){
				System.out.println(n);
			}
		}
		void sieve(int n){
			b = new boolean[n+1];
			b[0] = b[1] = true;
			for(int i = 2;i*i<n;i++){
				if(!b[i]){
					for(int j = 2*i;j<100001;j+=i) b[j] = true;
				}
			}
		}
		class Pair implements Comparable<Pair>{
			int u, v, i;
			
			Pair(int u, int v){
				this.u = u;
				this.v = v;
			}
			Pair(){
				
			}
			Pair(int u, int v, int i){
				this.u = u;
				this.v = v;
				this.i = i;
			}
			public int hashCode() {
				return Objects.hash();
			}
			public boolean equals(Object o) {
				Pair other = (Pair) o;
				return ((u == other.u && v == other.v)); 
			}
			public int compareTo(Pair other) {
				//return Integer.compare(val, other.val);
				return Long.compare(u, other.u) != 0 ? (Long.compare(u, other.u)) : (Long.compare(v,other.v));
			}
			public String toString(){
				return this.u +" " + this.v;
			}
		}
		int max(int a, int b){
			if(a>b) return a;
			return b;
		}
		public static class FenwickTree {
			
		    int[] array; // 1-indexed array, In this array We save cumulative information to perform efficient range queries and updates
	 
		    public FenwickTree(int size) {
		        array = new int[size + 1];
		    }
		    public int rsq(int ind) {
		        assert ind > 0;
		        int sum = 0;
		        while (ind > 0) {
		            sum += array[ind];
		            //Extracting the portion up to the first significant one of the binary representation of 'ind' and decrementing ind by that number
		            ind -= ind & (-ind);
		        }
		        return sum;
		    }
		    public int rsq(int a, int b) {
		        assert b >= a && a > 0 && b > 0;
		        return rsq(b) - rsq(a - 1);
		    }
		    public void update(int ind, int value) {
		        assert ind > 0;
		        while (ind < array.length) {
		            array[ind] += value;
		            //Extracting the portion up to the first significant one of the binary representation of 'ind' and incrementing ind by that number
		            ind += ind & (-ind);
		        }
		    }
		    public int size() {
		        return array.length - 1;
		    }
		}
		void buildGraph(int n){
			for(int i = 0; i<n ;i++){
				int x1 = ni() -1, y1 = ni()-1;
				amp[x1].add(y1);
				amp[y1].add(x1);
				x[i] = x1; y[i] = y1;
			}
		}
		long modInverse(long a, long mOD2){
	        return  power(a, mOD2-2, mOD2);
		}
		long power(long x, long y, long m)
		{
			if (y == 0)
	    return 1;
		long p = power(x, y/2, m) % m;
		p = (p * p) % m;
	 
		return (y%2 == 0)? p : (x * p) % m;
		}
		public long gcd(long a, long b){
			if(b==0) return a;
			return gcd(b,a%b);
		}
		static class ST1{
			int arr[], st[], size;
			ST1(int a[]){
				arr = a.clone();
				size = 10*arr.length;
				st = new int[size];
				build(0,arr.length-1,1);
			}
			void build(int ss, int se, int si){
				if(ss==se){
					st[si] = arr[ss];
					return;
				}
				int mid = (ss+se)/2;
				int val = 2*si;
				build(ss,mid,val); build(mid+1,se,val+1);
				st[si] = Math.min(st[val], st[val+1]);
			}
			int get(int ss, int se, int l, int r, int si){
				if(l>se || r<ss || l>r) return Integer.MAX_VALUE;
				if(l<=ss && r>=se) return st[si];
				int mid = (ss+se)/2;
				int val = 2*si;
				return Math.min(get(ss,mid,l,r,val), get(mid+1,se,l,r,val+1));
			}
		}
		static class ST{
			int arr[],lazy[],n;
			ST(int a){
				n = a;
				arr = new int[10*n];
				lazy = new int[10*n];
			}
			void up(int l,int r,int val){
				update(0,n-1,0,l,r,val);
			}
			void update(int l,int r,int c,int x,int y,int val){
				if(lazy[c]!=0){
					lazy[2*c+1]+=lazy[c];
					lazy[2*c+2]+=lazy[c];
					if(l==r)
						arr[c]+=lazy[c];
					lazy[c] = 0;
				}
				if(l>r||x>y||l>y||x>r)
					return;
				if(x<=l&&y>=r){
					lazy[c]+=val;
					return ;
				}
				int mid = l+r>>1;
				update(l,mid,2*c+1,x,y,val);
				update(mid+1,r,2*c+2,x,y,val);
				arr[c] = Math.max(arr[2*c+1], arr[2*c+2]);
			}
			int an(int ind){
				return ans(0,n-1,0,ind);
			}
			int ans(int l,int r,int c,int ind){
				if(lazy[c]!=0){
					lazy[2*c+1]+=lazy[c];
					lazy[2*c+2]+=lazy[c];
					if(l==r)
						arr[c]+=lazy[c];
					lazy[c] = 0;
				}
				if(l==r)
					return arr[c];
				int mid = l+r>>1;
				if(mid>=ind)
					return ans(l,mid,2*c+1,ind);
				return ans(mid+1,r,2*c+2,ind);
			}
		}
		public static int[] shuffle(int[] a, Random gen){
			for(int i = 0, n = a.length;i < n;i++)
			{ 
				int ind = gen.nextInt(n-i)+i; 
				int d = a[i]; 
				a[i] = a[ind];
				a[ind] = d; 
			} 
		return a; 
		}
		long power(long x, long y, int mod){
			long ans = 1;
			while(y>0){
				if(y%2==0){
					x = (x*x)%mod;
					y/=2;
				}
				else{
					ans = (x*ans)%mod;
					y--;
				}
			}
			return ans;
		}
	 
	 
		// To Get Input
		// Some Buffer Methods
		private byte[] inbuf = new byte[1024];
		public int lenbuf = 0, ptrbuf = 0;
	 
		private 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 boolean isSpaceChar(int c) {
			return !(c >= 33 && c <= 126);
		}
	 
		private int skip() {
			int b;
			while ((b = readByte()) != -1 && isSpaceChar(b))
				;
			return b;
		}
	 
		private double nd() {
			return Double.parseDouble(ns());
		}
	 
		private char nc() {
			return (char) skip();
		}
		private String ns() {
			int b = skip();
			StringBuilder sb = new StringBuilder();
			while (!(isSpaceChar(b))) { // when nextLine, (isSpaceChar(b) && b != '
										// ')
				sb.appendCodePoint(b);
				b = readByte();
			}
			return sb.toString();
		}
	 
		private 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);
		}
	 
		private char[][] nm(int n, int m) {
			char[][] map = new char[n][];
			for (int i = 0; i < n; i++)
				map[i] = ns(m);
			return map;
		}
	 
		private int[] na(int n) {
			int[] a = new int[n];
			for (int i = 0; i < n; i++)
				a[i] = ni();
			return a;
		}
	 
		private 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();
			}
		}
	 
		private 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();
			}
		}
	 
		private boolean oj = System.getProperty("ONLINE_JUDGE") != null;
	 
		private void tr(Object... o) {
			if (!oj)
				System.out.println(Arrays.deepToString(o));
		}
	} 