#include <bits/stdc++.h>

using namespace std;

int main()
{
    int t;
    cin>>t;
    while(t--){
        int n;
        cin>>n;
        string s;
        cin>>s;
        vector<int> v1;
        int count=0;
        for(int i=0;i<n;i++){
            if(s[i]!='1') v1.push_back(i+1);
            else count++;
        }
        int ans=0;
        if(count==n) cout<<ans<<endl;
        else {
            
        }
    }

    return 0;
}