You are given a string s consisting only of characters 0 and 1. A substring [l, r] of s is a string slsl + 1sl + 2... sr, and its length equals to r - l + 1. A substring is called balanced if the number of zeroes (0) equals to the number of ones in this substring.

You have to determine the length of the longest balanced substring of s.

Input

The first line contains n (1 ≤ n ≤ 100000) — the number of characters in s.

The second line contains a string s consisting of exactly n characters. Only characters 0 and 1 can appear in s.

Output

If there is no non-empty balanced substring in s, print 0. Otherwise, print the length of the longest balanced substring.

Examples

Input

8
11010111


Output

4


Input

3
111


Output

0

Note

In the first example you can choose the substring [3, 6]. It is balanced, and its length is 4. Choosing the substring [2, 5] is also possible.

In the second example it's impossible to find a non-empty balanced substring.

import java.util.*;
import java.io.*;
public class Solution {
	static FastScanner scr=new FastScanner();
//	static Scanner scr=new Scanner(System.in);
	static PrintStream out=new PrintStream(System.out);
	static StringBuilder sb=new StringBuilder();
	
	
	
	
	static class pair{
		int x;int y;
		pair(int x,int y){ 
			this.x=x;this.y=y;
			
		}
	}
	static class triplet{
		int x;
		long y;
		int z;
		triplet(int x,long y,int z){
			this.x=x;
			this.y=y;
			this.z=z;
		}
	}
	static class FastScanner {
		 BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
		StringTokenizer st=new StringTokenizer("");
	 	String next() {
	 		while (!st.hasMoreTokens())
	 			try {
	 				st=new StringTokenizer(br.readLine());
	 			} catch (IOException e) {
	 				e.printStackTrace();
	 			}
	 			return st.nextToken();
		} long gcd(long a,long b){
			if(b==0) {
				return a;
			}
				
			return gcd(b,a%b);
		}
	 	int[]  sort(int a[]) {
			 
	        int multiplier = 1, len = a.length, max = Integer.MIN_VALUE;
	        int b[] = new int[len];
	        int bucket[];
	        for (int i = 0; i < len; i++) if (max < a[i]) max = a[i];
	        while (max / multiplier > 0) {
	            bucket = new int[10];
	            for (int i = 0; i < len; i++) bucket[(a[i] / multiplier) % 10]++;
	            for (int i = 1; i < 10; i++) bucket[i] += (bucket[i - 1]);
	            for (int i = len - 1; i >= 0; i--) b[--bucket[(a[i] / multiplier) % 10]] = a[i];
	            for (int i = 0; i < len; i++) a[i] = b[i];
	            multiplier *= 10;
	        }
	        return a;
	    }
	 	 long modPow(long base,long exp) {
			if(exp==0) {
				return 1;
			}
			if(exp%2==0) {
				long res=(modPow(base,exp/2));
				return (res*res);
			}
			return (base*modPow(base,exp-1));
		}
		int []reverse(int a[]){
			int b[]=new int[a.length];
			int index=0;
			for(int i=a.length-1;i>=0;i--) {
				b[index]=a[i];
			}
			return b;
		}
		int nextInt() {
			return Integer.parseInt(next());
		}
		int[] readArray(int n) {
			int[] a=new int[n];
			for (int i=0; i<n; i++) a[i]=nextInt();
			return a;
		}
		long[] readLongArray(int n) {
			long  [] a=new long  [n];
			for (int i=0; i<n; i++) a[i]=nextLong();
			return a;
		}
		long nextLong() {
			return Long.parseLong(next());
		}
	}
	
	static void print(Object ele) {
		sb.append(ele).append(" ");
	}
	static void println(Object ele) {
		sb.append(ele).append('\n');
		
	}
	static void println() {
		sb.append('\n');
	}
//	static long LCM(long a,long b) {
//		return a*b/(scr.gcd(a, b));
//	}
//	static long n, m, k, l, q, count, sum, temp, ans;
//	static long []a;
//	static long b[];
//	static  char c[];
//	static char t[];
//	static boolean visited[][];
	
	static int count[];
	static void solve() {
		int n=scr.nextInt();
		int []a=new int[n];
		char c[]=scr.next().toCharArray();
		
		HashMap<Integer,Integer>hm=new HashMap<>();
		int sum=0;
		int len = 0;
		for(int i=0;i<n;i++) {
			sum+=(c[i]=='1')?1:-1;
			if(hm.containsKey(sum)) {
				len = Math.max(len, (i-hm.get(sum)));
			}else {
				hm.put(sum,i);
			}
			if(sum==0) {
				len=Math.max(len,i+1);
			}
		}
		out.println(len);
	}  
	static int  MAX = Integer.MAX_VALUE;
	static int  MIN = Integer.MIN_VALUE;
	public static void main(String []args) {
//		int t=scr.nextInt();
//		while(t-->0) {
//			solve();
//		}
		solve();
		out.println(sb);
	}
}