#include <iostream>

using namespace std;

int main ()
{
    int x,y,l;
    cin >> x >> y >> l;
    
    int cnt = abs(y)/l + abs(y)%l;
    cnt += abs(x)/l + abs(x)%l;

    if(y>0 && x!=0) { cnt+=1; }
    else if(y<0) { cnt+=2; }
    
    cout << cnt << endl;
    return 0;
}