n = raw_input()
m = raw_input()

if n.isdigit() == True and m.isdigit() == True:
    if int(n) >= 0 and int(n) <= 12345 and int(m) >= 0 and int(m) <= 12345:
        if len(str(n)) > 1 or len(str(m)) > 1:
            if n.startswith("0") == True and len(str(n)) > 1:
                print "NG"
            elif m.startswith("0") == True and len(str(m)) > 1:
                print "NG"
            else:
                print "OK"
        else:
            print "OK"
    else:
        print "NG"
else:
    print "NG"