Programming

Consider the following C program:
#include <stdio.h>
int counter = 0;
int calc (int a, int b) {
int c;
counter++;
if (b==3) return (a*a*a) ;
else {
c = calc (a, b/3) ;
return (c*c*c) ;
}
}
int main () {
calc (4, 81);
printf (“%d”, counter) ;
}
The output of this program is ______.