#include <library.h>

using namespace std;

const int squares[] = { 0, 1, 4, 9, 16, 25, 36, 49, 64, 81, 100, 121, 144 };
                      // obviously that array should be a lot longer

int binchop(const int q, const int first, const int last)
{ if (first > last)
    return -1;
  const int midpos = (first + last) / 2;
  const int midval = squares[midpos];
  if (q == midval)
    return midpos;
  else if (q < midval)
    return binchop(q, first, midpos - 1);
  else
    return binchop(q, midpos + 1, last); }

int main()
{ cout << "number: ";
  const int n = read_int();
  cout << binchop(n, 0, 12) << "\n"; }