#include <stdio.h>

int const MAXN = 16;

bool is_arithmetic(long long * a, int n)
{
	if (n <= 2)
		return true;
	long long d = a[1] - a[0];
	for (int i = 2; i < n; ++ i)
		if (a[i] - a[i - 1] != d)
			return false;
	return true;
}

bool is_geometric(long long * a, int n)
{
	if (n <= 2)
		return a[0] != 0 || a[1] == 0;
	for (int i = 2; i < n; ++ i)
		if (a[i] * a[0] != a[i - 1] * a[1])
			return false;
	return true;
}

int main()
{
	int n;
	long long a[MAXN];

	scanf("%d", &n);
	for (int i = 0; i < n; ++ i)
		scanf("%lld", &a[i]);

	int res = 0;
	if (is_arithmetic(a, n))
		res |= 1;
	if (is_geometric(a, n))
		res |= 2;

	char const * res_s[] = { "NONE", "ARITHMETIC", "GEOMETRIC", "BOTH" };
	printf("%s\n", res_s[res]);
	
	return 0;
}