#!/usr/bin/env python
#coding:utf8

def read():
    return map(int, raw_input().split())


def gcd(a, b):
    return a if b == 0 else gcd(b, a % b)


def work((N, D)):
    div = gcd(N, D)
    print N / div - 1


if __name__ == "__main__":
    work(read())