import std.stdio;
import std.conv;
import std.string;
import std.math;

void main()
{
    immutable x = readln.chomp.to!int;
    immutable y = readln.chomp.to!int;
    immutable l = readln.chomp.to!int;

    int step = abs(x) / l + (x % l != 0) + abs(y) / l + (y % l != 0);
    if (y < 0) {
        step += 2;
    } else if (x != 0) {
        ++step;
    }
    writeln(step);
}