#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using db = double;
using ull = unsigned long long;
#define ff(x) fixed << setprecision(x)
#define vel vector<long long>
#define vei vector<int>
#define ves vector<string>
#define asn ans
constexpr int inf = 0x3f3f3f3f;
constexpr ll INF = 0x3f3f3f3f3f3f3f3fLL;
constexpr db EPS = 1.0e-9;
constexpr ll MOD = 998244353LL;
constexpr ll SZ = 1e6;
constexpr ll MAXN5 = 2e5 + 5;
constexpr ll MAXN6 = 2e6 + 5;
ll n, m;

void Solve(void) {
    cin >> n;
    string s;
    cin >> s;
    int ans = 0;
    for (int i = 0; i < n; i++) {
        if (s[i] == '1') {
            ans++;
        }
    }
    if (n >= 3 && s[n - 1] == '1' && s[n - 2] == '0' && s[n - 3] == '1') {
        ans++;
    }
    cout << ans << '\n';
}
int main(void) {
    ios::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);
    // 	freopen("mine.in", "r", stdin);
    // 	freopen("mine.out", "w", stdout);

    int cas = 1;
    cin >> cas;
    while (cas--)
        Solve();
    return 0;
}