step by step please

For each of the calls to the following recursive method below, indicate what value is returned

public static int mystery(int n, int k) { if (k == 0 || k == n) {

 return 1; } else if (k > n) { 

 return 0; } else { 

return mystery(n - 1, k - 1) + mystery(n, k - 1); }

}

Call	Returns
mystery(4, 2)
mystery(4, 3)
mystery(5, -3)
mystery(5, 2)