#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#pragma GCC optimize("-ffloat-store")
#pragma GCC optimize("-fno-defer-pop")
long long int power(long long int a, long long int b, long long int m) {
  if (b == 0) return 1;
  if (b == 1) return a % m;
  long long int t = power(a, b / 2, m) % m;
  t = (t * t) % m;
  if (b & 1) t = ((t % m) * (a % m)) % m;
  return t;
}
long long int modInverse(long long int a, long long int m) {
  return power(a, m - 2, m);
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  int t;
  cin >> t;
  while (t--) {
    long long int i, j, k, l, n;
    cin >> n;
    char ar[n + 1];
    cin >> ar;
    if (ar[0] == '1' || ar[n - 1] == '1') {
      cout << (2 * n) << "\n";
      continue;
    }
    long long int mx = 0, c = 0;
    for (i = 0; i < n; i++) {
      c++;
      if (ar[i] == '1') {
        mx = max(mx, c + max(n - i, i + 1));
      }
    }
    c = 0;
    for (i = n - 1; i >= 0; i--) {
      c++;
      if (ar[i] == '1') {
        mx = max(mx, c + max(n - i, i + 1));
      }
    }
    c = 0;
    for (i = 0; i < n; i++) {
      if (ar[i] == '1') c++;
    }
    mx = max(mx, c + n);
    cout << mx << "\n";
  }
  return 0;
}
