#include <bits/stdc++.h>
#include <atcoder/all>
using mint = atcoder::static_modint<998244353>;
//using mint = atcoder::static_modint<1000000007>;
using namespace std;
using namespace atcoder;
using ld = long double;
using ll = long long;
#define mp(a,b) make_pair(a,b)
#define rep(i,s,n) for(int i=s; i<n; i++)

const int inf=2e9;
int main(){
    int n;
    cin >> n;
    vector<pair<int,int>> r(n);
    rep(i,0,n)cin >> r[i].first >> r[i].second;
    sort(r.begin(),r.end());
    multiset<int> S;
    rep(i,0,n){
        int a=r[i].first,b=r[i].second;
        auto itr=S.upper_bound(a);
        if(itr!=S.begin()){
            itr--;
            S.erase(itr);
            S.insert(b);
        }
        else S.insert(b);
    }
    cout << S.size()-1;
}