#include <bits/stdc++.h>

using namespace std;

#define llong long long int
#define ldouble long double
#define rep(i, n) for (int i = 0; i < n; ++i) 
#define stl_rep(itr, x) for (auto itr = x.begin(); itr != x.end(); ++itr)
#define stl_repr(itr, x) for (auto itr = x.begin(); itr != x.end(); ++itr)
#define all(x) x.begin(), x.end()
#define allr(x) x.rbegin(), x.rend()

const static int MOD = 1000000000 + 7;
const static int inf = INT_MAX / 2;
const static llong INF = 1LL << 31;
const static int dx[] = {1, 0, -1, 0};
const static int dy[] = {0, 1, 0, -1};

int main (int argc, char *argv[]) {
    cin.tie(0);
    ios::sync_with_stdio(false);

    int n;
    cin >> n;
    vector<int> L(n), R(n), dp;
    rep(i, n) cin >> L[i] >> R[i];
    dp.push_back(L[0]);
    for (int i = 1; i < n; ++i) {
        if (L[i] > dp.back()) {
            dp.push_back(L[i]);
        } else {
            if (R[i] <= dp.back()) {
                *lower_bound(all(dp), L[i]) = L[i];
            } else {
                dp.push_back(dp.back() + 1);
            }
        } 
    }

    cout << dp.size() << endl;
    
    return 0;
}