#include <iostream>

int main(void) {
	int X, Y, L;
	scanf("%d%d%d", &X, &Y, &L);
	
	int ans = 0;
	if(X != 0) ans = 1;
	if(Y < 0) ans = 2;
	
	X = abs(X), Y = abs(Y);
	if(X != 0) ans += (X - 1) / L + 1;
	if(Y != 0) ans += (Y - 1) / L + 1;
	
	printf("%d", ans);
	return 0;
}