#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); i++)
using namespace std;
typedef long long ll;

int main(){
    cin.tie(0);
    ios::sync_with_stdio(0);
    
    int N,M; cin >> N >> M;
    vector<pair<int,int>> A(M);
    for(auto &[L, R] : A) cin >> L >> R;
    sort(A.begin(), A.end(), [](auto I, auto J) {
        if(I.second == J.second) return I.first < J.first;
        return I.second < J.second;
    });

    int LAST = -1e9;
    int ans = 0;
    for(auto [L, R] : A) {
        if(LAST < L) {
            LAST = R;
            ans++;
        }
    }

    ans = N - ans;
    cout << ans << endl;
}