#include <iostream>
#include <string>
#include <algorithm>
#include <cmath>

using namespace std;

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

    int dir = 0;
    dir += ceil((double)abs(x)/l);
    dir += ceil((double)abs(y)/l);
    if(x && y) dir++;
    else if(x) dir++;
    if(y < 0) dir++;


    cout << dir << endl;

    return 0;
}