#include <iostream>
#include <algorithm>
#include <vector>

using namespace std;

typedef pair<int, int> PII;

int n;
vector<PII> seg, res;

void merge()
{
    int st = -2e9, ed = -2e9;

    for (auto item : seg)
    {
        if (ed < item.first)                            //该段末尾小于下段开头
        {
            if (st != -2e9) res.push_back({st, ed});    //储存这一段
            st = item.first, ed = item.second;          //更新下一段
        }
        else
        {
            ed = max(ed, item.second);                  //两段合并为一段，只要挪动ed即可
        }
    }

    if (st != -2e9) res.push_back({st, ed});            //判空并处理最后一段
}                                                       //题目给出n不为0，所以不用这个if判空也能通过

int main()
{
    cin >> n;
    while (n -- )
    {
        int l, r;
        cin >> l >> r;
        seg.push_back({l, r});
    }

    sort(seg.begin(), seg.end());

    merge();

    cout << res.size() << endl;

    return 0;
}