function Main(input) {
	input = input.split("\n");
	tmp = input[0].split(" ");
 
	var a = parseInt(tmp[0], 10);
	var b = parseInt(tmp[1], 10);
 
    var ans = a - b;
    if(ans < 0) {
        ans = 0;
    }
	console.log('%d',ans);
}
Main(require("fs").readFileSync("/dev/stdin", "utf8"));