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

int main()
{
    int n, m;
    cin >> n >> m;
    vector<pair<int, int>> seg(m);
    for (int i = 0; i < m; i++)
    {
        cin >> seg.at(i).second >> seg.at(i).first;
    }
    sort(seg.begin(), seg.end());
    int current = -1, ans = n;
    for (int i = 0; i < m; i++)
    {
        auto [r, l] = seg.at(i);
        if (l <= current)
        {
            continue;
        }
        current = r;
        ans--;
    }
    cout << ans << endl;
    return 0;
}