Holidays

Description:

Input:

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.

Output:

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.

Sample Input:

10 5
1 2
3 3
4 6
7 7
8 10

Sample Output:

OK

Sample Input:

10 5
1 2
2 3
4 5
7 8
9 10

Sample Output:

2 2

Sample Input:

10 5
1 2
3 3
5 7
7 7
7 10

Sample Output:

4 0

Note:

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.