#include <bits/stdc++.h>
using namespace std;

int main(){
    int X,Y,L,ans = 0;
    cin >> X >> Y >> L;

    if(X == 0){
        ans = (Y+ L - 1) / L;
    }else if (Y >= 0){
        ans = (Y + L - 1)/ L + (abs(X) + L - 1) / L + 1;
    }else{
        ans = (abs(Y) + L - 1)/ L + (abs(X) + L - 1) / L + 2;
    }
    
    cout << ans;
}