#include <stdio.h>
 
int rec(int n){
	if(n==0){
		return -2;
	}
	else{
		return 2*rec(n-1)+3;
	}
}
 
int main(void){
 
	int n;
	n=4;
	return 0;
 
}
				I2luY2x1ZGUgPHN0ZGlvLmg+CgppbnQgcmVjKGludCBuKXsKCWlmKG49PTApewoJCXJldHVybiAtMjsKCX0KCWVsc2V7CgkJcmV0dXJuIDIqcmVjKG4tMSkrMzsKCX0KfQoKaW50IG1haW4odm9pZCl7CgkKCWludCBuOwoJbj00OwoJcHJpbnRmKCIlZCIscmVjKG4pKTsKCXJldHVybiAwOwoJCn0=