#include<bits/stdc++.h>
using namespace std;

#define ll long long

void solve()
{
    int n; cin>>n;
    string s; cin>>s;
    int cnt=0;
    for(int i=0; i<s.size(); i++){
        if(s[i]=='1') cnt++;
    }
    cout<<cnt<<endl;
}

int main()
{
    int t; cin>>t;
    while(t--) solve();
}