What is the time complexity in big-O notation of this algorithm?

execute(int n, String start, String auxiliary, String end) {

if (n == 1)

{

System.out.println("Disk " + n + " : " + start + " to " + end);

}

else

{

execute(n - 1, start, end, auxiliary);

System.out.println("Disk " + n + " : " + start + " to " + end);

execute(n - 1, auxiliary, start, end);

}

}