The following recursive method calculates 3n : // precondition: n > = 0 public int power3(int n) { if (n == 0) // if n equals to 0 return 1; else { int p = power3(n/2); // when n is odd, n/2 is truncated to an integer // e. g., 7/2 gives 3 and 1/2 gives 0 p *= p; // multiply p by itself if (n % 2 == 1) // if n is odd p *= 3; // multiply p by 3 return p; } } how many multiplications will be performed when the program calls power3(15)?