#include <stdio.h>
#include <math.h>

int main() {
	double integral = 0.0f;
	double fractional = 0.0f;
	double num = 100.0f;
	
	fractional = modf(num, &integral);
	
	if ((num >= 0) && (fractional == 0.0))
	{
		printf("Natural!\n");
	}
	else
	{
		printf("Unnatural.\n");
	}
	
	return 0;
}