#include <bits/stdc++.h>
#define FOR(a,b) for(int a=0;a<b;a++)

using namespace std;

typedef long long ll;


int main()
{
    ll d;
    cin>>d;
    ll ar[3];
    FOR(ctr1,3) cin>>ar[ctr1];
    ll rez1=-1,rez2=-1;
    if(ar[1]>1)
    {
        ll l=0LL,r=0LL;
        ll d1=ar[0LL]-ar[1]+1;
        if(d1>0LL)
        {
            l+=ceil((double)d1/d);
        }
        ll d2=ar[2]-ar[1]+1;
        if(d2>0LL)
        {
            r+=ceil((double)d2/d);
        }
        if(max(ar[0LL]-l*d,0LL)==max(ar[2]-r*d,0LL))
        {
            if(max(ar[0LL]-(l+1)*d,0LL)!=max(ar[2]-r*d,0LL))
                l++;
            else
            {
                l=-1;
            }
        }
        if(l!=-1)
            rez1=l+r;
    }
    if(ar[0LL]>0LL && ar[2]>0LL)
    {
        ll l=0LL,m=0LL;
        ll dm=max(ar[1]-min(ar[0LL]-1,ar[2]-1),0LL);
        m=ceil((double)dm/d);
        if(ar[0LL]==ar[2]){
            l++;
            if(max(ar[0LL]-l*d,0LL)==max(ar[1]-m*d,0LL)){
                m++;
                if (max(ar[0LL]-l*d,0LL)==max(ar[1]-m*d,0LL)){
                    l=-1;
                }
            }
        }
        if(l!=-1)
            rez2=l+m;
    }
    if(rez1==-1)
        cout<<rez2<<endl;
    else if(rez2==-1)
        cout<<rez1<<endl;
    else cout<<min(rez1,rez2)<<endl;
    return 0;
}
/*
5 7 1 12349583

*/