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


int main()
{
    int n, k;
    cin >> n >> k;
    vector<pair<int,int>> f(k);
    for(int i = 0;i < k;i++ ) {
        int a, b;
        cin >> a >> b;
        f[i] = {a, b};
    }
    sort(f.begin(), f.end());
    
    int ans = 0;
    
    int legszelso = f[0].second;
    if(f[0].first != 1) ans++;
    
    for(int i = 0;i< k;i++ ) {
        if(legszelso < f[i].first) {
            ans++;
            legszelso = f[i].second;
        }
    }
    
    if(f[k-1].second != n) ans++;
    
    cout << ans << endl;
    
    return 0;
}