# -*- coding: utf-8 -*-
"""
No.333 門松列を数え上げ
https://yukicoder.me/problems/no/333

"""
import sys
from sys import stdin
input = stdin.readline


def solve(A, B):
    if A == B:
        return 0
    if A < B:
        return A - 1
    if A > B:
        return 2000000000 - A


def main(args):
    A, B = map(int, input().split())
    ans = solve(A, B)
    print(ans)


if __name__ == '__main__':
    main(sys.argv[1:])