#include<iostream>
#include<string>
#include<string.h>
#include<algorithm>
#include<stdio.h>
#include<cmath>
#include<vector>
#include<utility>
#include<stack>
#include<queue>
#include<list>
#include<bitset>

#define FOR(i, a, b) for(int i=(a);i<=(b);i++)
#define RFOR(i, a, b) for(int i=(a);i>=(b);i--)
#define MOD 1000000007
#define INF 1000000000

using namespace std;


int main(void) {
	int x, y, l;
	int count = 0;

	cin >> x >> y >> l;

	if (y < 0) {
		count += 2;
	}
	if (x != 0) {
		count++;
	}
	if (abs(x)%l == 0) {
		count += abs(x) / l;
	}
	else {
		count += abs(x) / l + 1;
	}
	if (abs(y) %l == 0) {
		count += abs(y) / l;
	}
	else {
		count += abs(y) / l + 1;
	}
	cout << count << endl;
	return 0;
}