CF44C.Holidays

School holidays come in Berland. The holidays are going to continue for n days. The students of school №_N_ are having the time of their lives and the IT teacher Marina Sergeyevna, who has spent all the summer busy checking the BSE (Berland State Examination) results, has finally taken a vacation break! Some people are in charge of the daily watering of flowers in shifts according to the schedule. However when Marina Sergeyevna was making the schedule, she was so tired from work and so lost in dreams of the oncoming vacation that she perhaps made several mistakes. In fact, it is possible that according to the schedule, on some days during the holidays the flowers will not be watered or will be watered multiple times. Help Marina Sergeyevna to find a mistake.

贝尔兰的学校假期开始了。假期将持续 $n$ 天。第 $N$ 号学校的学生们正尽情享受假期时光，而信息技术老师玛丽娜·谢尔盖耶夫娜则终于得以休假——她整个夏天都在忙着批阅贝尔兰国家考试（BSE）的成绩。
按照排班表，每天由不同人员轮班负责给花浇水。然而，玛丽娜·谢尔盖耶夫娜在制定这份排班表时，因工作过度疲惫，又沉浸在即将到来的假期美梦中，可能犯下了一些错误。事实上，根据该排班表，在假期中的某些天里，花可能完全未被浇水，也可能被浇了多次水。
请帮助玛丽娜·谢尔盖耶夫娜找出这些错误。

The first input line contains two numbers n and m (1 ≤ n, m ≤ 100) — the number of days in Berland holidays and the number of people in charge of the watering respectively. The next m lines contain the description of the duty schedule. Each line contains two integers a__i and b__i (1 ≤ a__i ≤ b__i ≤ n), meaning that the i-th person in charge should water the flowers from the a__i-th to the b__i-th day inclusively, once a day. The duty shifts are described sequentially, i.e. b__i ≤ a__i + 1 for all i from 1 to n - 1 inclusively.

第一行输入包含两个整数 $n$ 和 $m$（$1 ≤ n, m ≤ 100$）——分别表示 Berland 国假期的天数以及负责浇花的人数。接下来的 $m$ 行描述值班安排。每行包含两个整数 $a_i$ 和 $b_i$（$1 ≤ a_i ≤ b_i ≤ n$），表示第 $i$ 位负责人需在第 $a_i$ 天至第 $b_i$ 天（含首尾两天）每天浇一次花。值班班次按顺序给出，即对所有 $i$（$1 ≤ i ≤ m - 1$），均有 $b_i ≤ a_{i+1}$。

Print "OK" (without quotes), if the schedule does not contain mistakes. Otherwise you have to find the minimal number of a day when the flowers will not be watered or will be watered multiple times, and output two integers — the day number and the number of times the flowers will be watered that day.

如果日程安排中没有错误，则输出 "OK"（不带引号）。否则，你需要找出花朵未被浇水或被多次浇水的最早一天，并输出两个整数——该天的天数编号以及当天浇水的次数。

Keep in mind that in the second sample the mistake occurs not only on the second day, but also on the sixth day, when nobody waters the flowers. However, you have to print the second day, i.e. the day with the minimal number.

请注意，在第二个样例中，错误不仅发生在第二天，还发生在第六天（当天无人给花浇水）。但是，您必须输出第二天，即编号最小的那一天。