from re import fullmatch

a = input()
b = input()

pat = '[0-9]|[1-9]\d|[1-9]\d\d|[1-9]\d{3}|1[01]\d{3}|12[012]\d\d|123[0-3]\d|1234[0-5]'

ans = 'NG'

if fullmatch(pat, a):
    if fullmatch(pat, b):
        ans = 'OK'

print(ans)