#include <cstdio>
#include <iostream>
#include <algorithm>
#include <functional>
#include <vector>
#include <utility>
#include <memory.h>

using namespace std;

int
main()
{
    vector<pair<int, int> > vec;
    int nr_intervals;
    int seg_begin(0x7FFFFFFF), seg_end(0);
    int previous1, previous2;
    int nr_elements(0);

    //freopen("test.txt", "r", stdin);
    ios::sync_with_stdio(false);

    cin >> nr_intervals;
    for (int i = 0; i != nr_intervals; ++i) {
        int t1, t2;

        cin >> t1 >> t2;
        seg_begin = min(t1, seg_begin);
        seg_end = max(t2, seg_end);
        vec.push_back(make_pair(t1, t2));
    }

    sort(vec.begin(), vec.end(), greater<pair<int, int> >());
    vec.reserve(vec.size());

    previous1 = vec.front().first;
    previous2 = vec.front().first + 1;
    nr_elements = 2;
    for (vector<pair<int, int> >::iterator iter = vec.begin() + 1, iter_end = vec.end(); iter != iter_end; ++iter) {
        // Obviously, previous2 > previous1.
        if (iter->second < previous1) {
            // None in our set is included by range *iter.
            nr_elements += 2;
            previous1 = iter->first;
            previous2 = iter->first + 1;
        } else if (iter->second < previous2) {
            // It is easy to figure out that iter->second is larger or equal to previous1 if we get here.
            nr_elements += 1;
            previous2 = previous1;
            previous1 = iter->first;
        } // Or the entire range specified by *iter is satisfied by our set.
    }

    cout << nr_elements << endl;

    return 0;
}