function Main(input) {
    var tmp = input.split("\n");
    var x = parseInt(tmp[0], 10);
    var y = parseInt(tmp[1], 10);
    var l = parseInt(tmp[2], 10);

    ans = minStep(x, y, l);
    console.log('%d', ans);

    function minStep(x, y, l) { 
        var absX = Math.abs(x);
        var absY = Math.abs(y);
        if(x === 0 && y === 0) {
            return 4;
        } else if(y === 0) {
            return minLineStep(l, absX);
        } else if(x === 0) {
            return minLineStep(l, absY);
        } else {
            return minLineStep(l, absX) + minLineStep(l, absY) + 1;
        }
    }

    function minLineStep(l, x) {
        return Math.floor((x + l - 1)/l);
    }
}

// Don't edit this line!
Main(require("fs").readFileSync("/dev/stdin", "utf8"));