#include <iostream>
#include <cmath>
using namespace std;

void susumu(int xy,int l,int *cou)
{
    if(xy != 0 && xy % l != 0){
        *cou += abs(xy) / l + 1;
    }else{
        *cou += abs(xy) / l;
    }
    return;
}

void magaru(int *cou)
{
    *cou += 1;
    return;
}

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

    int count = 0;
    if(Y > 0){
        susumu(Y,L,&count);
        if(X != 0){
            magaru(&count);
            susumu(X,L,&count);
        }
    }else{
        magaru(&count);
        susumu(X,L,&count);
        if(Y < 0){
            magaru(&count);
            susumu(Y,L,&count);
        }
    }
    if(X == 0 && Y == 0) count = 0;

    cout << count << endl;

    return 0;
}