using System;
using System.Linq;

class Program
{
    static void Main(string[] args)
    {
        string[] AB = Console.ReadLine().Split(' ');
        long A = long.Parse(AB[0]);
        long B = long.Parse(AB[1]);

        long max = 2000000000;
        long min = 0;

        if (A < B)
        { max = A - 1; }
        else { min = A; }

        Console.WriteLine(max - min);
    }
}