Sub0 : #1 #2 #3 #4 #5 #6 #7 AC

#include<bits/stdc++.h>
using namespace std;
int n,a[20001],d[20001],ans=INT_MIN,b,g;
int main(){
	cin>>n;
	for(int i=1;i<=n;i++){
		cin>>a[i];
		if(a[i]==0)a[i]=-1;
		d[i]=d[i-1]+a[i];
	
	}
	for(int i=1;i<=n;i++){
		for(int j=1;j<=i;j++){
			if(d[i]-d[j-1]==0)ans=max(ans,i-j+1);
		}
	}
	if(ans<0)ans=0;
	cout<<ans;
}