function main(input){
	var x = 2, y = Number(input), z, a = x * y;
	if (x < y) {
		t = x;
		x = y;
		y = t;
	}

	z = x % y;
	while (z !== 0) {
		x = y;
		y = z;
		z = x % y;
	}

	console.log(a / y);
}
     
main(require("fs").readFileSync("/dev/stdin", "utf8"));