#include <iostream>
int main(){
  unsigned char n;
  std::cin >> n;
  n -= '0';
  std::cout << (bool)(n & 1) + (bool)(n &  (1 << 1))  + (bool)(n &  (1 << 2))  + (bool)(n &  (1 << 3))  + (bool)(n &  (1 << 4));
  return 0;
}