a = input()
b = input()
if (len(a) > 1 and a[0] == '0') or (len(b) > 1 and b[0] == '0'):
    print("NG")
    exit()
try:
    a = int(a)
    b = int(b)
    if 0 <= a <= 12345 and 0 <= b <= 12345:
        print("OK")
    else:
        print("NG")
except:
    print("NG")