#include <bits/stdc++.h>
using namespace std;

int main() {
    int n;
    cin >> n;
    
    vector<pair<int, int>> range(n);  // ????A[i]????? [L_i, R_i]
    for (int i = 0; i < n; ++i) {
        cin >> range[i].first >> range[i].second;
    }
    
    // ??????????dp[value]??????? value ???????????
    map<int, int> dp;  // ??map?????value???LIS??

    // ??????
    for (int i = 0; i < n; ++i) {
        int L = range[i].first, R = range[i].second;
        map<int, int> new_dp = dp;  // ???????????dp

        // ????? [L, R] ????
        for (int v = L; v <= R; ++v) {
            // ??????v?????dp[v]
            auto it = dp.lower_bound(v);
            if (it != dp.begin()) {
                --it;  // ????v????
                new_dp[v] = max(new_dp[v], it->second + 1);
            } else {
                // ??????v??????????????1???
                new_dp[v] = max(new_dp[v], 1);
            }
        }
        
        // ?????dp????dp?
        dp = new_dp;
    }

    // ????dp?????
    int maxLIS = 0;
    for (auto& entry : dp) {
        maxLIS = max(maxLIS, entry.second);
    }

    cout << maxLIS << endl;
    return 0;
}