#include <stdio.h>
int a(int n){
if(n==0){
return 0;
}
else{
return 3*a(n-1)+4;
}
}
int main(void) {
int n;
n=2;
return 0;
}
I2luY2x1ZGUgPHN0ZGlvLmg+CmludCBhKGludCBuKXsKCWlmKG49PTApewoJCXJldHVybiAwOwoJfQoJZWxzZXsKCQlyZXR1cm4gMyphKG4tMSkrNDsKCX0KfQppbnQgbWFpbih2b2lkKSB7CglpbnQgbjsKCW49MjsKCXByaW50ZigiJWQiLGEobikpOwoJcmV0dXJuIDA7Cn0K