#define _USE_MATH_DEFINES
#include <algorithm>
#include <cstdio>
#include <functional>
#include <iostream>
#include <cfloat>
#include <climits>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <map>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <time.h>
#include <vector>
using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> i_i;
typedef pair<ll, int> ll_i;
typedef pair<double, int> d_i;
typedef pair<ll, ll> ll_ll;
typedef pair<double, double> d_d;
struct edge { int u, v; ll w; };

ll MOD = 1000000007;
ll _MOD = 1000000009;
double EPS = 1e-10;

int solve(int a, int b, int c, int d) {
	if (b < a && b < c && a != c) return 0;
	if (b > a && b > c && a != c) return 0;
	if (d == 0) return -1;
	int cnt = 0;
	if (a == c) {
		if (a == 0) return -1;
		cnt++;
		a = max(a, a - d);
	}
	int x = (b - min(a, c) + d - 1) / d;
	if (min(a, c) == 0) x = INT_MAX;
	int y = (max(0, a - b + 1) + d - 1) / d + (max(0, c - b + 1) + d - 1) / d;
	if (b == 0) y = INT_MAX;
	int z = min(x, y);
	if (z == INT_MAX) return -1;
	return z + cnt;
}

int main() {
	int d, a, b, c; cin >> d >> a >> b >> c;
	cout << solve(a, b, c, d) << endl;
}