#include <bits/stdc++.h>
using namespace std;

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    
    int N,M; cin >> N >> M;
    vector<pair<int,int>> answer;
    int back = -1,streak = 0;
    while(M--){
        int a; cin >> a;
        if(back+streak != a){
            if(back != -1) answer.push_back({back,streak});
            back = a,streak = 1;
        }
        else streak++;
    }
    answer.push_back({back,streak});
    cout << answer.size() << "\n";
    for(auto [s,l] : answer) cout << s << " " << l << endl;
}