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


#define all(x) (x).begin(), (x).end()
#define sz(x) (int) (x).size()
#define int long long
const int mod = 1e9 + 7, INF = 1e18 + 3, N = 2e5 + 2;


void solve(int cs){
    int n; cin >> n;
    string s; cin >> s;
    s = '#' + s;
    int mxo = 0, mxz = 0;
    int nw = 0;
    for(int i = 1 ; i <= n ; i++){
        if(s[i] != s[i -1]){
            if(s[i - 1] == '1') mxo = max(mxo, nw);
            else mxz = max(mxz, nw);
            nw = 1;
        }
        else nw++;
    }
    //debug(mxo);

    if(nw){
        if(s[n] == '1') mxo = max(mxo, nw);
        else mxz = max(mxz, nw);
    }

    cout<<mxz<<'\n';
}

//It's now, or never.
signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    int TEST = 1;
    cin >> TEST;

    for (int i = 1; i <= TEST; i++) {
      //  cout << "Case " << i << ":"<<'\n';
        solve(i);
    }
 
    return 0;
}