#include <bits/stdc++.h>
using namespace std;
//#include <atcoder/all>
//using namespace atcoder;
using ll=long long;
using Graph=vector<vector<pair<int,pair<int,int>>>>;
#define MAX 1000000
#define MOD 1000000007
#define INF 1000000000

int main(){
  int N,M;
  cin>>N>>M;
  vector<pair<int,int>> lr(M);
  for(int i=0;i<M;i++){
    cin>>lr[i].first>>lr[i].second;
  }
  sort(lr.begin(),lr.end());

  priority_queue<int,vector<int>,greater<int>> pq;
  int i=0;
  int cnt=0;
  while(i<M){
    if(i<M&&pq.empty()){
      pq.push(lr[i].second);
      i++;
    }
    while(i<M&&lr[i].first<=pq.top()){
      pq.push(lr[i].second);
      i++;
    }
    cnt++;
    while(!pq.empty()){
      pq.pop();
    }
  }
  cout<<N-cnt<<endl;
}