#include <iostream>
using namespace std;
int main(){
    int X,Y,L,cnt=0;
    cin >> X >> Y >> L;
    if(Y>=0 && X!=0)cnt+=1;
    if(Y<0 && X!=0)cnt+=2;
    if(Y<0 && X==0)cnt+=3;
    cnt+=(abs(X)+L-1)/L+(abs(Y)+L-1)/L;
    cout << cnt << endl;
    return 0;
}