#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
struct el {
    ll l, r;
} m[200005];
bool cmp(el a, el b) {
    if (a.l != b.l)
        return a.l < b.l;
    return a.r > b.r;
}
void test(int n) {
    for (int i = 0; i < n; i++) printf("%lld %lld\n", m[i].l, m[i].r);
}
int main() {
    std::ios::sync_with_stdio(false);
    ll n, p;
    cin >> n >> p;
    for (int i = 0; i < p; i++) {
        cin >> m[i].l >> m[i].r;
    }
    sort(m, m + p, cmp);
    //	test(p);
    ll ans, start, tail;
    ans = 1;
    start = m[0].r;
    tail = m[0].r;
    ll pre = 0;
    while (tail < n && pre < p) {
        while (m[pre].l <= start + 1 && pre < p) {  // start+1��Ϊ���ҵ���һ���ܹ���Ϊ���俪ʼ�ĵ�
            tail = max(tail, m[pre].r);
            pre++;
        }
        start = tail;
        ans++;
    }
    cout << ans;
    return 0;
}