#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
using mint = modint998244353;
using vi = vector<int>;
using vvi = vector<vi>;
using vvvi = vector<vvi>;
using vll = vector<ll>;
using vvll = vector<vll>;
using vvvll = vector<vvll>;
using vmi = vector<mint>;
using vvmi = vector<vmi>;
using vvvmi = vector<vvmi>;
#define all(a) (a).begin(), (a).end()
#define rep2(i, m, n) for (int i = (m); i < (n); ++i)
#define rep(i, n) rep2(i, 0, n)
#define drep2(i, m, n) for (int i = (m)-1; i >= (n); --i)
#define drep(i, n) drep2(i, n, 0)
using p = pair<int, int>;
void solve(){
    
}

int main(){

    int n, m; cin >> n >> m;
    vi a(m); rep(i, m)cin >> a[i];
    int s = 0, now = a[0];
    vector<p> v;
    rep2(i, 1, m){
        if(a[i] - now > 1){
            v.push_back({a[s], i-s});
            cout << a[s] << " " << i-s << endl;
            s = i;
        }
        now = a[i];
    }v.push_back({a[s], m-s});
    cout << v.size() << endl;
    for(auto i : v)cout << i.first << " " << i.second << endl;
    return 0;
}