function Main(input) {
    var line = input.split("\n");
    var X = +line[0];
    var Y = +line[1];
    var L = +line[2];
    var count = 0;

    if (X != 0) {
        count += 1;
        count += Math.ceil(Math.abs(X) / L);
        if (Y != 0) {
            count += 1;
            count += Math.ceil(Math.abs(Y) / L);
        }
    }

    if( X == 0 && Y > 0){
        count += Math.ceil(Y / L);
    } else {
        count += 2;
        count += Math.ceil(Math.abs(Y) / L);
    }
    
    console.log(count);
}

Main(require("fs").readFileSync("/dev/stdin", "utf8"));