import std.stdio,
       std.conv,
       std.string,
       std.range,
       std.math,
       std.bigint,
       std.algorithm;

void main()
{
    auto input = readln.split.to!(long[]);
    auto A = input[0], B = input[1];

    (abs(B - A) - 1 + A < B ? A - 1 : 2000000000 - A).writeln;
}