#include<bits/stdc++.h>
using namespace std;
long long n,xs[1001000],a=-0x3f3f3f3f,b=-0x3f3f3f3f,c=-0x3f3f3f3f,minn=0x3f3f3f3f;
long long ans=0x3f3f3f3f;
int main(){
    freopen("Unnamed_Problem.in","r",stdin);
    freopen("Unnamed_Problem.out","w",stdout);
    cin>>n;
    for(int i=1;i<=n;i++){
        cin>>xs[i];
    }
    sort(xs+1,xs+1+n);
    for(int i=1;i<=n;i++){
        if(xs[i]>0)minn=min(minn,xs[i]);
    }
    if(minn!=xs[1]){
    b=xs[n];c=xs[1];a=minn;
    ans=min(ans,-((b*b)/(4*a))+c);
    }
    else{
        b=xs[n];c=xs[1];a=xs[2];
        ans=min(ans,-((b*b)/(4*a))+c);
        b=xs[n];c=xs[2];a=xs[1];
        ans=min(ans,-((b*b)/(4*a))+c);
    }
    cout<<ans<<endl;
    return 0;
}