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