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

int main() {
    int tt;
    cin >> tt;
    while (tt--) {
        int n;
        cin >> n;
        string s;
        cin >> s;
        vector<int> cnt(2);
        for (int i = 0; i < n; i++) {
            cnt[s[i] - '0']++;
        }
        cnt[0] = min(cnt[0], cnt[1] + 1);
        cnt[1] = min(cnt[1], cnt[0] + 1);
        cout << cnt[0] + cnt[1] << endl;
    }
    return 0;
}