/* -*- coding: utf-8 -*-
 *
 * 281.cc: No.281 門松と魔法(1) - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

/* typedef */

/* global variables */

/* subroutines */

/* main */

int main() {
  int d, h0, h1, h2;
  cin >> d >> h0 >> h1 >> h2;

  if (h1 == 0 && (h0 == 0 || h2 == 0)) {
    puts("-1");
    return 0;
  }

  // h0 < h1 > h2
  int c0 = 0;
  if (h0 >= h1) c0 += (h0 - h1) / d + 1;
  if (h2 >= h1) c0 += (h2 - h1) / d + 1;

  // h0 > h1 < h2
  int mh = min(h0, h2);
  int c1 = 0;
  if (h1 >= mh) c1 += (h1 - mh) / d + 1;

  printf("%d\n", min(c0, c1));
  return 0;
}