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

int main(){
  int n,m;
  cin>>n>>m;
  vector<int> vec;
  vector<int> a(m);
  for (int i=0;i<m;i++) cin>>a[i];
  a.push_back(2e9);
  vector<pair<int,int>> ans;
  for (int i=0;i<=m;i++){
    if (vec.empty()||vec.back()+1==a[i]) vec.push_back(a[i]);
    else{
      ans.push_back({vec[0],vec.size()});
      vec.clear();
      vec.push_back(a[i]);
    }
  }
  cout<<ans.size()<<endl;
  for (auto [s,l]:ans) cout<<s<<" "<<l<<endl;
}