#include <iostream>
using namespace std;

int maxDepth, steps, bestSteps;

int doit(const string& s, int curDep, int i)
{
  if (s[i] == '0')
    return 1;

  ++steps;
  ++curDep;
  if (curDep > maxDepth)
  {
    maxDepth = curDep;
    bestSteps = steps;
  }

  int l = 1;
  l += doit(s, curDep, i + l);
  l += doit(s, curDep, i + l);
  return l;
}

int main()
{
  string s;
  for (int c = 0; c < 10; ++c)
  {
    cin >> s; cin >> s;
    maxDepth = -1, steps = 0, bestSteps = -1;
    doit(s, 0, 0);
    cout << bestSteps << endl;
  }
}