def f(a,b):
    if (len(a)>1 and a[0]=='0')or(b[0]=='0'and len(b)>1):return'NG'
    try:a=int(a);b=int(b)
    except:return'NG'
    if 0<=a<12346 and 0<=b<12346:return'OK'
    return'NG'
print(f(input(),input()))