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

int LIS(vector<int>& A) {
    vector<int> dp;
    for (int x : A) {
        auto it = lower_bound(dp.begin(), dp.end(), x);
        if (it == dp.end()) dp.push_back(x);
        else *it = x;
    }
    return dp.size();
}

int simulatedAnnealing(int n, vector<pair<int, int>>& range) {
    vector<int> A(n);
    for (int i = 0; i < n; i++) {
        A[i] = rand() % (range[i].second - range[i].first + 1) + range[i].first;
    }

    int bestLIS = LIS(A);
    vector<int> bestA = A;

    double temperature = 100.0;
    double coolingRate = 0.995;

    while (temperature > 1e-6) {
        int idx = rand() % n;
        int oldVal = A[idx];
        A[idx] = rand() % (range[idx].second - range[idx].first + 1) + range[idx].first;

        int newLIS = LIS(A);

        if (newLIS > bestLIS) {
            bestLIS = newLIS;
            bestA = A;
        } else {
            double prob = exp((newLIS - bestLIS) / temperature);
            if (rand() / double(RAND_MAX) < prob) {
                bestLIS = newLIS;
                bestA = A;
            } else {
                A[idx] = oldVal;
            }
        }

        temperature *= coolingRate;
    }

    return bestLIS;
}

int main() {
    int n;
    cin >> n;
    vector<pair<int, int>> range(n);
    for (int i = 0; i < n; i++) {
        cin >> range[i].first >> range[i].second;
    }
    int res = 0;
    for (int i = 1; i <= 10;i++ )
    	res = max(res, simulatedAnnealing(n, range));
	cout<<res;
    return 0;
}