Testcase missing?

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problem code : CHRL4
#include <bits/stdc++.h>
using namespace std;

int main() {
// your code goes here
int n,k;
cin>>n>>k;
int a[n];
long long p=1;
for(int i=0;i<n;i++)
cin>>a[i];
sort(a,a+n);

for(int i=n-1;i>0;)
{
    p=p*a[i];
    
    if(i-k<0)
    i=0;
    else
    i=i-k;
    
}
cout<<p;
return 0;

}