Question: https://www.codechef.com/problems/CPERM

My Solution: https://www.codechef.com/viewsolution/12147288

I know that the solution to this problem is (2^(N-1) - 2) and I also know that the efficient way to find powers of 2 is by bitwise shift operator but I don’t know y i am getting WA.

Here is the code:

```
#include <iostream>
using namespace std;
int main() {
// your code goes here
int T,N;
cin>>T;
while(T--)
{
cin>>N;
long long int ans = (1<<(N-1))-2;
cout<<ans<<"\n";
}
return 0;
}
```

Please can anyone find the mistake in my code.