#include <iostream>
#include <algorithm>
#include <queue>
#include <utility>
using namespace std;
typedef pair<int, int> P;

const int MAX_N = 200000;
int N;
P r[MAX_N];

int main() {
    cin >> N;
    for (int i = 0; i < N; i++)
        cin >> r[i].second >> r[i].first;
    int ans = -1, tmp = 0;
    sort(r, r + N);
    queue<P> que1, que2;
    for (int i = 0; i < N; i++)
        que1.push(r[i]);
    while (!que1.empty()) {
        P mat = que1.front(); que1.pop();
        if (mat.second >= tmp) {
            tmp = mat.first;
        } else
            que2.push(mat);
        if (que1.empty()) {
            swap(que1, que2);
            ans++;
            tmp = 0;
        }
    }
    cout << ans << endl;
    return 0;
}