#!/usr/bin/env python
#-*-coding:utf-8-*-

'''
n! means n × (n − 1) × ... × 3 × 2 × 1
For example, 10! = 10 × 9 × ... × 3 × 2 × 1 = 3628800,
and the sum of the digits in the number 10! is 3 + 6 + 2 + 8 + 8 + 0 + 0 = 27.
Find the sum of the digits in the number 100!
'''

from math import factorial

if __name__ == '__main__':
    print sum(map(int, list(str(factorial(100)))))

add problem 20