#include <algorithm>
#include <cstdio>
#include <cstdlib>
#include <cctype>
#include <cmath>
#include <iostream>
#include <queue>
#include <list>
#include <stack>
#include <map>
#include <numeric>
#include <set>
#include <sstream>
#include <string>
#include <vector>
using namespace std;
#define REP(i,a,n) for(int i=(a); i<(int)(n); i++)
#define rep(i,n) REP(i,0,n)
#define FOR(it,c) for(__typeof((c).begin()) it=(c).begin(); it!=(c).end(); ++it)
#define ALLOF(c) (c).begin(), (c).end()
typedef long long ll;

int main(){
  ll d, H1, H2, H3;
  cin >> d;
  cin >> H1 >> H2 >> H3;
  ll ret = 1000000000000LL;

  if(H1<H2 && H2>H3 && H1!=H3){
    cout << 0 << endl;
    return 0;
  }
  if(H1>H2 && H2<H3 && H1!=H3){
    cout << 0 << endl;
    return 0;
  }
  
  if(d==0){
    cout << -1 << endl;
    return 0;
  }

  //真ん中が最大を目指す場合
  {
    ll h1=H1, h2=H2, h3=H3;
    ll cnt = 0;
    if(h1>=h2){
      cnt += (h1-h2)/d + 1;
      h1-=((h1-h2)/d + 1)*d;
    }
    if(h1<0) h1=0;
    if(h2<=h3){
      cnt += (h3-h2)/d + 1;
      h3-=((h3-h2)/d + 1)*d;
    }
    if(h3<0) h3=0;

    if(h1!=h3){
      ret = min(ret, cnt);
    }else{
      if(h1>0) ret = min(ret, cnt+1);
    }
  }
  //真ん中が最小を目指す場合
  {
    ll h1=H1, h2=H2, h3=H3;
    ll cnt = 0;
    if(h1==h3){
      cnt += 1;
      h1-=d;
    }
    if(h1<0) h1=0;
    ll mn = min(h1, h3);
    if(mn > h2){
      ret = min(ret, cnt);
    }else{
      if(mn != 0){
        cnt += (h2-mn)/d + 1;
        ret = min(ret, cnt);
      }
    }
  }

  if(ret == 1000000000000LL){
    cout << -1 << endl;
  }else{
    cout << ret << endl;
  }
  return 0;
}