#include <bits/stdc++.h>
#include <atcoder/all>

using namespace std;
using namespace atcoder;
typedef long long ll;
typedef modint998244353 mint;
//typedef modint1000000007 mint;

void chmin(ll& a, ll b) { a = min(a, b); }
void chmax(ll& a, ll b) { a = max(a, b); }

int main() {
    int N, M;
    cin >> N >> M;
    vector<int> A(M);
    for(int i = 0; i < M; i++) cin >> A[i];
    int S = -1;
    vector<pair<int,int>> ans;
    for(int i = 0; i < M; i++){
        if(S == -1){
            S = A[i];
        }
        if(i == M-1 || A[i] + 1 != A[i+1]){
            ans.push_back({S, A[i]-S+1});
            S = -1;
        }
    }
    cout << ans.size() << endl;
    for(int i = 0; i < ans.size(); i++){
        cout << ans[i].first << " " << ans[i].second << endl;
    }
}