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

int main() {
  int N, M; cin >> N >> M;
  vector<int> A(M); for (int &B : A) cin >> B;
  vector<pair<int, int>> Ans;
  for (int i = 0; i < M; i++) {
    int j = 1;
    while (i + j < M && A.at(i + j) == A.at(i) + j) j++;
    Ans.push_back({A.at(i), j});
    i += j - 1;
  }
  cout << Ans.size() << endl;
  for (pair<int, int> P : Ans) cout << P.first << ' ' << P.second << endl;
}