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

struct interv
{
    int a;
    int b;
};
bool comp(interv a, interv b)
{
    return a.a < b.a;
}
int main()
{
    int mx;
    int darab;
    cin >> mx >> darab;
    vector<interv> vek;
    interv temp;
    for(int i = 0; i < darab; i++)
    {
      cin >> temp.a >> temp.b;
      vek.push_back(temp);
    }
    sort(vek.begin(), vek.end(), comp);
    vector<interv> vek2;
    vek2.push_back(vek[0]);

    for(int i = 1; i < vek.size(); i++)
    {
        if(vek2[vek2.size()-1].b >= vek[i].a)
            vek2[vek2.size()-1].b = max(vek[i].b,vek2[vek2.size()-1].b);
        else vek2.push_back(vek[i]);
    }
    int szam = vek2.size()-1;
    if(vek2[0].a > 1) szam++;
    if(vek2[vek2.size()-1].b < mx) szam++;
    cout << szam;

}