MY code :

#include<bits/stdc++.h>
using namespace std;
int n,l,r,a[55],cnt,tmp1=100000,tmp2;
int main(){
	cin>>n;
	for(int i=1;i<=n;i++){
		cin>>a[i];
		tmp1=min(a[i],tmp1);
		tmp2=max(a[i],tmp2);
	}
	cin>>l>>r;
	//cout<<tmp1<<" "<<tmp2;
	//return 0;
	for(int i=1;i<=1000;i++){
		if(tmp1>=l&&tmp1<=r&&tmp2>=l&&tmp2<=r){
			cout<<cnt;
			return 0;
		}
		tmp2--;
		tmp1++;
		cnt++;
	}
	cout<<-1;
	return 0;
}