#include <bits/stdc++.h>

using namespace std;

//typedef
//------------------------------------------
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<string> VS;
typedef pair<int, int> PII;
typedef long long LL;

//container util
//------------------------------------------
#define ALL(a)  (a).begin(),(a).end()
#define RALL(a) (a).rbegin(), (a).rend()
#define PB push_back
#define MP make_pair
#define SZ(a) int((a).size())
#define EACH(i,c) for(typeof((c).begin()) i=(c).begin(); i!=(c).end(); ++i)
#define EXIST(s,e) ((s).find(e)!=(s).end())
#define SORT(c) sort((c).begin(),(c).end())

//repetition
//------------------------------------------
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n)  FOR(i,0,n)

//constant
//--------------------------------------------
const double EPS = 1e-10;
const double PI  = acos(-1.0);

int main(){
  cin.tie(0);
  ios_base::sync_with_stdio(false);

  LL d, h1, h2, h3, add = 0, ans = 1e10;
  cin >> d >> h1 >> h2 >> h3;
  if(h1 == h3){
	if(h1 == 0){
	  cout << -1 << endl;
	  return 0;
	}
	++add;
	h1 = max(0LL, h1-d);
  }
  if(min(h1,h3) > 0){
	LL dh = h2 - min(h1,h3);
	if(dh < 0) ans = 0;
	else ans = dh / d + 1;
  }

  LL tmp = 0;
  if(h1 >= h2){
	if(h1 == 0)
	  tmp = 1e10;
	else{
	  tmp += (h1-h2)/d+1;
	  h1 -= min(h1, tmp * d);
	}
  }
  if(h3 >= h2){
	if(h3 == 0)
	  tmp = 1e10;
	else{
	  tmp += (h3-h2)/d+1;
	  h3 -= min(h3, d*((h3-h2)/d+1));
	}
  }
  if(h1 == h3){
	if(h1 == 0)
	  tmp = 1e10;
	else
	  ++tmp;
  }

  ans = min(ans, tmp);
  cout << (ans>=1e10? -1: ans+add) << endl;
  
  return 0;
}