#include<stdio.h>
#include<math.h>
int isPerfect(int n){
	int cmp = sqrt(n);
	return (cmp * cmp == n);
}
int isFibo(int n){
	return (isPerfect(5*n*n - 4) || isPerfect(5*n*n + 4));
}
int main(){
	int n;
	printf("Fibonancci checker. if you want to stop, enter 0[0]\n");
	while(1){
		scanf("%d", &n);
		if(n == 0) break;
		if(isFibo(n)) printf("yep\n");
		else printf("nope\n");
	}
	return 0;
}