#include<iostream>
#include<cstdio>
#include<vector>
#include<queue>

#include<map>
#include<set>
#include<string>
#include<algorithm>
#include<functional>
using namespace std;
#define FOR(i,a,b) for (int i=(a);i<(b);i++)
#define RFOR(i,a,b) for (int i=(b)-1;i>=(a);i--)
#define REP(i,n) for (int i=0;i<(n);i++)
#define RREP(i,n) for (int i=(n)-1;i>=0;i--)
#define INF 1<<30
#define MP make_pair
#define mp make_pair
#define pb push_back
#define PB push_back
#define DEBUG(x) cout<<#x<<": "<<x<<endl
#define ll long long
#define ull unsigned long long



int main(){
	cin.tie(0);
	ios::sync_with_stdio(false);
	int d;cin>>d;
	int h[3];
	cin>>h[0]>>h[1]>>h[2];
	if(h[0]==0 && h[1]==0 && h[2]==0){
		cout<<-1<<endl;return 0;
	}
	
	if((h[1]<h[0] && h[1]<h[2]) ||
			(h[1]>h[0] && h[1]>h[2])){
		cout<<0<<endl;return 0;
	}
	int c =( h[1] - min(h[0],h[2]) )/ d + 1;
	int b =(max(h[0],h[2]) - h[1] ) / d +1;
	cout<<min(c,b)<<endl;

}