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

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    int N; cin >> N;
    vector<pair<long long,long long>> rR(N);
    for(auto &[r,R] : rR) cin >> r >> R;
    sort(rR.rbegin(),rR.rend());

    multiset<long long> S;
    for(auto &[r,R] : rR){
        auto itr = S.lower_bound(R);
        if(itr == S.end()) S.insert(r);
        else S.erase(itr),S.insert(r);
        
    }
    cout << S.size()-1 << endl;
}