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

const long long INF = 1LL << 60;
#define MOD 1000000007;

typedef long long ll;

#define writeln(n) cout<<n<<endl;
#define rep(i,n) for(int i=0; i<n; i++);

typedef pair<float, float> P;

typedef pair<string, int> Psi;

int main() {

	int x,y,l;

	cin>>x>>y>>l;

	int cnt=0;
	if(x !=0){
		int nx = abs(x-0);
		cnt += nx/l;

		if(nx%l !=0){
			cnt +=nx%l;
		}

		cnt++;
	}

	if(y !=0){

			int ny = abs(y-0);
			cnt += ny/l;

			if(ny%l !=0){
				cnt +=ny%l;
			}

			cnt +=2;

		}

	if(y >=0){
		cnt--;
	}

	writeln(cnt);

}