#include <string>
#include <iostream>
//1000000000000000000000000000000000000000
using namespace std;

int rek(long long x, int a, int moves, long long result, int length){
  if(x == result){
    return moves;
  }
  if(moves > 8)
    return 100;
    
  int firstZero = 0;
  for(int i =0; i < length; i++){
    int digit = (x >> i) % 2;
    if(digit == 0)
      firstZero = length - i;
  }
  
  int min = 100;
  for(int i = a + 1; i < firstZero + 2; i++){
    long long mask = x >> i;
    
    int res = rek(x | mask, i, moves+1, result, length);
    if(res < min)
      min = res;
  }
  
  return min;
}

int main() {
  cin.sync_with_stdio(false);
  cin.tie(nullptr);
  
  string stevilo = "";
  cin >> stevilo;
  
  if(stevilo[0] == '0'){
    cout << "-1" << "\n";
    return 0;
    }
    
  int digits = stevilo.size();
  long long number = 0;
  for (int i = 0; i < stevilo.size(); i++){
    char c = stevilo[i];
    if(c == '1'){
    number += ((long long)1) << (digits - i - 1);
    }
  }    
  long long result = (((long long)1) << digits) - 1;
  //cout << number << "\n";
  //cout << result << "\n";
  
  cout << (rek(number, 0, 0, result, digits)) << "\n";
  
  return 0;
}