自己看

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
ll t,n;
string s;
int main(){
	//freopen(".in","r",stdin);
	//freopen(".out","w",stdout);
	std::ios::sync_with_stdio(false);
	std::cin.tie(nullptr);
	std::cout.tie(nullptr);
	cin>>t;
    while(t--){
        cin>>n>>s;
        ll i=0,j=n-1;
        while(i<j&&s[i]!=s[j]){
            i++;
            j--;
        }
        cout<<j-i+1<<endl;
    }
	//fclose(stdin);
	//fclose(stdout);
	return 0;
}
//coder::by::M91