#include <iostream>

std::string s;
int maxDepth, steps, bestSteps, p;

void doit(int curDep)
{
  if (s[p++] == '0') return;
  ++steps;
  if (++curDep > maxDepth) maxDepth = curDep, bestSteps = steps;
  doit(curDep), doit(curDep);
}

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