#include <cstdio>
#include <cstring>
#include <iostream>
#include <string>
#include <cmath>
#include <bitset>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <algorithm>
#include <complex>
#include <unordered_map>
#include <unordered_set>
#include <random>
#include <cassert>
#include <fstream>
#include <utility>
#include <functional>
#include <time.h>
#include <stack>
#include <array>
#include <list>
#include <atcoder/all>
#define popcount __builtin_popcount
using namespace std;
using namespace atcoder;
typedef long long ll;
typedef pair<int, int> P;

int main()
{
    ll n;int m; cin>>n>>m;
    vector<P> v(m);
    for(int i=0; i<m; i++){
        cin>>v[i].second>>v[i].first;
    }
    ll ans=0;
    sort(v.begin(), v.end());
    int pr=-1;
    for(int i=0; i<m; i++){
        if(pr<v[i].second){
            pr=v[i].first;
            ans++;
        }
    }
    ans=n-ans;
    cout<<ans<<endl;
    return 0;
}