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

using namespace std;

typedef pair<int, int> PII;

void merge(vector<PII> &segs)
{
    vector<PII> res;

    //注意一定要先将区间排序，PII排序首先排序first再排序second
    sort(segs.begin(), segs.end());

    int st = -2e9, ed = -2e9;//维护的当前区间,题目范围是(-1e9,1e9) 所以初始化为(-2e9,-e29)
    for (auto seg : segs)
        if (ed < seg.first)
        {
            if (st != -2e9) res.push_back({st, ed});//特判是否是第一个区间
            st = seg.first, ed = seg.second;
        }
        else ed = max(ed, seg.second);//seg.second有可能比ed小

    if (st != -2e9) res.push_back({st, ed});//循环退出后最后一个区间还未加入res,并且判断st防止segs中没有区间

    segs = res;
}

int main()
{
    int n;
    scanf("%d", &n);

    vector<PII> segs;
    for (int i = 0; i < n; i ++ )
    {
        int l, r;
        scanf("%d%d", &l, &r);
        segs.push_back({l, r});
    }

    merge(segs);

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

    return 0;
}