#include <iostream>
#include <math.h>
using namespace std;
int main(void){
    // Your code here!
    float x,y,l,moveCount = 0;
    
    cin >> x >> y >> l;
    moveCount += ceil(abs(y) / l);
    moveCount += ceil(abs(x) / l);
    if(y < 0)moveCount += 2;
    else if(x == 0);
    else moveCount += 1;
    
    cout << moveCount;
    
}