#include <iostream>

int calcDistance(int dist, int stride) {
    int step = 0;
    if (dist<0) dist = -dist;
    
    while(step*stride < dist) {
        step += 1;
    }
    
    return step;
}

int main() {
    int X, Y, L;
    int step = 0;
    
    std::cin >> X >> Y >> L;
    
    if (Y < 0) step += 2;
    else if (X != 0) step += 1;
    
    step += calcDistance(X, L);
    step += calcDistance(Y, L);

    std::cout << step << std::endl;

	return 0;
}