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

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


def work((A, B)):
    if A < B:
        print (A - 1) + (B - A - 1)
    else:
        print (2000000000 - A) + (A - B - 1)


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