#include <cstdlib>
#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <stack>
#include <queue>
#include <cmath>
#define rep(i,n) for (int i=0;i<(n);i++)
#define debug(x) cout<<#x<<": "<<x<<endl

using namespace std;

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);
    
    int x = 0, y = 0, k = 0, cnt = 0;
    cin >> x >> y >> k;
    
    if (x == 0 && y >= 0){ }
    else if (y >= 0){ cnt++;}
    else { cnt+=2;}
        
    cnt += ceil(abs((double)x) / k);
    cnt += ceil(abs((double)y) / k);
    
    cout << cnt << endl;
    system("PAUSE");
    return EXIT_SUCCESS;
}