Q21

Consider the following $\text{C}$ 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 ______.