python题解，抛弃大脑

import sys


def p(n, m):
    if n == 0 or m == 0:
        return 0
    res = n
    for i in range(n-m+1, n):
        res *= i
    return res


for line in sys.stdin:
    line = line.strip()
    if not line:
        continue
    a, b = map(int, line.split())
    res = p(a, b)
    bres = bin(res)[2:]
    if res == 0:
        print()
    else:
        print(len(bres) - bres.rfind('1')-1)