#include <bits/stdc++.h>

using namespace std;

typedef pair<int, int> PII;

const int N = 1e5 + 100;

int n;
vector<PII> segs;

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


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

    int start = -2e9, end = -2e9;
    // 注意这里end也是-2e9，因为是从左边来的，不能是2e9,否则就比不了啦！
    for(auto seg: segs){
        if(end < seg.first){
            if(start != -2e9){
                res.push_back({start, end});
            }
            start = seg.first, end= seg.second;

        }else{
            end = max(end, seg.second);
        }
    }

    // 将最后一段合并区间也放入答案中
    if(start != -2e9)
        res.push_back({start, end});

    segs = res;
}

int main(){
    cin >> n;

    for(int i = 0; i < n; i ++){
        int l, r;
        cin >> l >> r;

        segs.push_back({l, r});
    }

    merge(segs);

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

    return 0;

}