#include"bits/stdc++.h"
using namespace std;
using ll = long long;
using ld = long double;
#define rep(i,m,n) for(ll i=(ll)m;i<(ll)n;i++)
#define Endl endl
#define pr(i,j) make_pair(i,j) 
const ll mod = 998244353;
const ll inf = 5e18;
const ld pi = 3.14159265358979;
int main() {
	ll x, y, l;
	cin >> x >> y >> l;
	if (y > 0 && x == 0) {
		cout << (y - 1) / l + 1 + 0;
	}
	else if (y > 0 && x != 0) {
		cout << (y - 1) / l + 1 + (abs(x) - 1) / l + 1 + 1;
	}
	else if (y == 0 && x == 0) {
		cout << 0 << endl;
	}
	else if (y == 0 && x != 0) {
		cout << (abs(x) - 1) / l + 1 + 1;
	}
	else if (y < 0 && x == 0) {
		cout << (abs(y) - 1) / 1 + 1 + 2;
	}
	else if (y < 0 && x != 0) {
		cout << (abs(y) - 1) / l + 1 + (abs(x) - 1) / l + 1 + 2;
	}
}