i=input
a=i()
b=i()
for i in a:
	if not i.isdigit(): print('NG'); exit()
for i in b:
	if not i.isdigit(): print('NG'); exit()
if 0 <= int(a) <= 12345 and (int(a) == 0 or a[0] != '0') and 0 <= int(b) <= 12345 and (int(b) == 0 or b[0] != '0'):
	print('OK')
else:
	print('NG')