from sys import stdin
from ctypes import *

class mpz(Structure):
  _fields_ = [
    ("_mp_alloc", c_int),
    ("_mp_size", c_int),
    ("_mp_d", POINTER(c_void_p))
  ]

def solve():
  gmp = cdll.LoadLibrary("/usr/lib64/libgmp.so.10")
  n = mpz()
  gmp.__gmpz_init_set_str(byref(n), stdin.read())
  gmp.__gmp_printf("%d\n", gmp.__gmpz_popcount(byref(n)))

solve()