process.stdin.resume();
process.stdin.setEncoding('utf8');
process.stdin.on('data', function(chunk) {
    main(chunk.trim());
});

var MAX_VALUE = 2*Math.pow(10,9);
function main(chunk){
    // your code goes here
    var lines = chunk.split(" ");
    var a1 = Number(lines[0]);
    var a2 = Number(lines[1]);
    console.log(a1<a2?a2-2:MAX_VALUE-a2-1);
}