Testcase 2 is not passing

#1

I dnt know why my 2nd testcase is not passing.Can you please check my code and tell me.

#include<bits/stdc++.h>
using namespace std;
int main() {
int n;
cin>>n;
long long int mx=0,ar[n];

for(int i=0;i<n;i++)
{
    cin>>ar[i];
   
}
for(int i=0;i<n;i++)
{
   mx=max(mx,ar[i]); 
   
}

 
cout<<mx<<endl;
return 0;

}

#2

If all number are negative then ur ans will always be 0.

#3

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