try:
    ans='OK'
    a,b=input(),input()
    if (len(a)>1 and a[0]=='0') or (len(b)>1 and b[0]=='0'):
        ans='NG'
    a,b=int(a),int(b)
    if ans=='NG':
        print(ans)
    elif 0<=a+b<=12345*2:
        print('OK')
    else:
        print('NG')
except:
    print('NG')