def is_int(s):
    try:
        int(str(s))
        return True
    except ValueError:
        return False

A = str(input())
B = str(input())
if is_int(A) and is_int(B):
    if A == str(int(A)) and B == str(int(B)):
        print("OK")
    else:
        print("NG")
else:
    print("NG")