Array-Max value in array

#1

#include
using namespace std;
int main() {
long long int n,temp=0;
cin>>n;
const int size=n;
int arr[size];
int max=arr[0];
for(int i=0;i<n;i++){

cin>>arr[i];}
for(int i=0;i<n;i++)
{

     if(max<arr[i])
       {
           temp=arr[i];
           max=arr[i];
           max=temp;
       } 
    
}
cout<<max<<endl;

return 0;

}
why this code not passing any test case in this problem and still it is successfully passing on other idide

#2

Read the constraints given in the ques carefully. The range of numbers is -1000000000 to 1000000000 while in the given code data type is taken as int.