#include <bits/stdc++.h>

using namespace std;

void fast_io() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
}

int main() {
    fast_io();
    int n, m;
    cin >> n >> m;
    vector<int> l(m), r(m);
    for (int i = 0; i < m; i++) {
        cin >> l[i] >> r[i];
    }
    vector<int> ii(m);
    iota(ii.begin(), ii.end(), 0);
    sort(ii.begin(), ii.end(), [&](int i, int j) { return r[i] < r[j]; });
    int la = 0, ans = n;
    for (int i : ii) {
        if (l[i] > la) {
            la = r[i];
            ans--;
        }
    }
    cout << ans << endl;
}