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

#define rep(i,n) for(i=0; i<n; ++i)
#define in(a) cin >> a
#define out(a,b) cout << a << b
using namespace std;
using lint = long long;

int main(void){
    int i, j, n, m, k, cnt = 0;
    lint x, y, l;
    in(x);
    in(y);
    in(l);
    if(x==0&&y==0);
    else if(y<=0){
        if(y==0){
            cnt++;
            cnt+=abs(x)/l;
            if(abs(x)%l!=0) cnt++;
        }
        else{
            cnt+=2;
            if(x==0){
                cnt+=abs(y)/l;
                if(abs(y)%l!=0) cnt++;
            }
            else{
                cnt+=abs(y)/l;
                if(abs(y)%l!=0) cnt++;
                cnt+=abs(x)/l;
                if(abs(x)%l!=0) cnt++;
            }
            
        }
    }
    else{
        if(x==0){
            cnt+=abs(y)/l;
            if(abs(y)%l!=0) cnt++;

        }
        else{
            cnt++;
            cnt+=abs(y)/l;
            if(abs(y)%l!=0) cnt++;
            cnt+=abs(x)/l;
            if(abs(x)%l!=0) cnt++;
        }
    }
    out(cnt,endl);
    return 0;
}