#include <iostream>

using namespace std;

int main(){
    int x,y,k;
    //x:東西
    //y:北南
    cin >> x >> y >> k;
    int ans = 0;
    if(x != 0)ans += 1;
    if(x != 0 && y < 0)ans += 1;
    if(x == 0 && y < 0)ans += 2;
    ans += abs(y)/k;
    ans += abs(x)/k;
    if(y%k != 0)ans += 1;
    if(x%k != 0)ans += 1;
    cout << ans << endl;
    return 0;
}