package main

import (
	"fmt"
)

func main() {
	var n, m int
	if _, err := fmt.Scan(&n, &m); err != nil {
		return
	}

	counts := make([]int, n+1)
	for i := 0; i < m; i++ {
		var a, b int
		fmt.Scan(&a, &b)
		for j := a; j <= b; j++ {
			if j <= n {
				counts[j]++
			}
		}
	}

	for i := 1; i <= n; i++ {
		if counts[i] != 1 {
			fmt.Println(i, counts[i])
			return
		}
	}

	fmt.Println("OK")
}