#include <list>
#include <iostream>
#include <vector>
#include <bitset>
#include <algorithm>

#define MOD ((long long) 1e9 + 7)

using namespace std;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(NULL);

    int n, m;
    cin >> n >> m;

    vector<pair<int, int>> carriage(m+1);

    for (int i = 0; i < m; i++) {
        cin >> carriage[i].first >> carriage[i].second;
    }
    carriage[m] = pair<int, int>(n, 0);

    sort(carriage.begin(), carriage.end());

    int empty_at = carriage[0].second;
    int empty_intervals = 0;
    for (int i = 1; i < m+1; i++) {
        if (empty_at < carriage[i].first) empty_intervals++;
        empty_at = max(empty_at, carriage[i].second);
    }

    cout << empty_intervals;

    return 0;
}