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

#define REP(i, n) for(int i=0; i<(n); i++)

int X,Y,L;
signed main()
{
    cin>>X>>Y>>L;
    int cnt = 0;
    if (Y > 0) {
        cnt += (Y+L-1)/L;
    } else if (Y < 0) {
        Y *= -1;
        cnt += (Y+L-1)/L + 1;
        if (X == 0) cnt++;
    }
    if (X != 0) {
        cnt += (abs(X)+L-1)/L + 1;
    }
    cout << cnt << endl;
    return 0;
}