// やけくそTLE解.

//#define _GLIBCXX_DEBUG
#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define rep(i, n) for (ll i = 0; i < (ll)(n); i++)
#define all(a) (a).begin(), (a).end()
const ll INF32 = 2e9;
const ll INF64 = 4e18;

void printYN(bool ok){
    if(ok)cout << "Yes" << endl;
    else cout << "No" << endl;
    return;
}

signed main() {
    int N, M;
    cin >> N >> M;
    int now = -1, i = 0, cnt = 0;
    vector<pair<int, int>> out;
    while(i<M){
        int ai;
        cin >> ai;
        if(now==-1){
            now = ai;
            cnt = 1;
        }
        else if(ai-now==1){
            now = ai;
            cnt++;
        }
        else {
            out.push_back({now-cnt+1,cnt});
            now = ai;
            cnt = 1;
        }
        i++;
    }
    out.push_back({now-cnt+1,cnt});
    cout << out.size() << endl;
    rep(i, out.size())cout << out[i].first << " " << out[i].second << endl;
    return 0;
}