def gcd(*numbers: int) -> int:
    if len(numbers) == 1:
        return numbers[0]
    if len(numbers) == 2:
        a, b = numbers
        if a < b:
            a, b = b, a

        while True:

            if a % b == 0:
                return b
            a, b = b, a % b

    first_gcd = gcd(*numbers[:2])
    return gcd(first_gcd, *numbers[2:])


def main():
    N, D = map(int, input().split())
    ND_gcd = gcd(N, D)
    N, D = N // ND_gcd, D // ND_gcd

    if N % D == 0:
        print(N // D - 1)
    else:
        print(N - 1)


if __name__ == "__main__":
    main()