#include <iostream>
#include <cmath>
using namespace std;

int main(){
    int x = 0, y = 0, l = 0, res = 0;
    cin >> x >> y >> l;

    if(y < 0){ res += 2; }
    else if(x != 0){ res += 1; }

    x = abs(x); y = abs(y);
    res += (x+l-1)/l;
    res += (x+l-1)/l;
    cout << res << endl;
    
    return 0;
}