#include <stdio.h>
int hugu(int a){
	if(a<2){
		return 1;
	}else{
		return hugu(a-2)+2*hugu(a-1);
	}
}
 
int main(void) {
   int x=hugu(4);
	return 0;
}
 
 
				I2luY2x1ZGUgPHN0ZGlvLmg+CmludCBodWd1KGludCBhKXsKCWlmKGE8Mil7CgkJcmV0dXJuIDE7Cgl9ZWxzZXsKCQlyZXR1cm4gaHVndShhLTIpKzIqaHVndShhLTEpOwoJfQp9CgppbnQgbWFpbih2b2lkKSB7CiAgIGludCB4PWh1Z3UoNCk7CiAgIHByaW50ZigiJWQiLHgpOwoJcmV0dXJuIDA7Cn0KCg==