function Main(input) {
	input = input.split(" ");
	var a = Math.ceil(input[0]/input[2])*input[2];
	var b = Math.floor(input[1]/input[2])*input[2];
	console.log(((b-a)/input[2])+2);
}Main(require("fs").readFileSync("/dev/stdin", "utf8").trim());