A = input()
B = input()

def isValid(A, B):
    if not isValidNumber(A):
        return False
    if not isValidNumber(B):
        return False
    return True

def isValidNumber(A):
    if not isAllNumber(A):
        return False
    if A[0] == '0' and len(A) > 1:
        return False
    if int(A) > 12345:
        return False
    return True

def isAllNumber(A):
    for c in A:
        if c not in '0123456789':
            return False
    return True

if isValid(A, B):
    print('OK')
else:
    print('NG')