You are given 2 qubits which are guaranteed to be in one of the four orthogonal states:

Your task is to perform necessary operations and measurements to figure out which state it was and to return the index of that state (0 for , 1 for etc.). The state of the qubits after the operations does not matter.

You have to implement an operation which takes an array of 2 qubits as an input and returns an integer.

Your code should have the following signature:

namespace Solution {
    open Microsoft.Quantum.Primitive;
    open Microsoft.Quantum.Canon;
operation Solve (qs : Qubit[]) : Int
{
    body
    {
        // your code here
    }
}

}