#include<iostream>
#include<vector>
#include<algorithm>

using namespace std;
const int N = 1e6 + 10;
typedef pair<int, int> pii;
vector<pii> segs;
int n;

void merge(vector<pii> &segs) {
    vector<pii> res;

    sort(segs.begin(), segs.end());
    int ed = -1e9;
    for (auto seg:segs) {
        if (ed < seg.first) {
            res.push_back({seg.first, seg.second});
            ed = seg.second;
        } else {
            ed = max(ed, seg.second);
        }
    }

    segs = res;
}

int main() {

    cin >> n;
    for (int i = 0; i < n; i++) {
        int l, r;
        cin >> l >> r;
        segs.push_back({l, r});
    }
    merge(segs);
    cout << segs.size();
}