package main

import . "fmt"
import . "os"
import bf "bufio"

func main() {
	rd := bf.NewReader(Stdin)
	var n,m int
	Fscan(rd,&n,&m)
	s,c := -1,0
	ss,ll := make([]int,0,m),make([]int,0,m)
	for ;m>0;m-- {
		var a int
		Fscan(rd,&a)
		if a-s > 1 {
			if c != 0{
				ll = append(ll, c)
			}
			ss = append(ss, a)
			c = 0
		}
		s = a
		c++
	}
	ll = append(ll, c)
	Println(len(ss))
	for i := range ss {
		Println(ss[i], ll[i])
	}
}