#include <bits/stdc++.h>
using namespace std;
long long n, ans;
string str;
long long solve() {
  cin >> n >> str;
  long long x = -1, y = -1;
  long long i = 0;
  while (i < n) {
    if (str[i] == '1') {
      x = i;
      break;
    }
    i++;
  }
  i = n - 1;
  while (i >= 0) {
    if (str[i] == '1') {
      y = i;
      break;
    }
    i--;
  }
  ans = n;
  if (x != -1) {
    ans = max(ans, 2 * (x + 1));
    ans = max(ans, 2 * (n - x));
  }
  if (y != -1) {
    ans = max(ans, 2 * (y + 1));
    ans = max(ans, 2 * (n - y));
  }
  cout << ans << "\n";
  return 0;
}
signed main() {
  ios::sync_with_stdio(0);
  long long t = 1;
  cin >> t;
  while (t--) solve();
  return 0;
}
