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

// #include<ext/pb_ds/assoc_container.hpp>
// #include<ext/pb_ds/tree_policy.hpp>
// using namespace __gnu_pbds;
// typedef tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update> pbds; // find_by_order, order_of_key


#define IOS ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define endl "\n"
#define int long long
const int inf = 1e18;


// int dx[4]={-1,0,1,0};
// int dy[4]={0,1,0,-1};

// int dx[8]={0,-1,-1,-1,0,1,1,1};
// int dy[8]={1,1,0,-1,-1,-1,0,1};

const int N = 200200;
const int mod = 1e9+7;
using ii = pair<int,int>;

//write on copy

void solver(){
    int n;
    cin>>n;

    multiset<ii>s;

    for(int i=0;i<n;i++)
    {
        int a,b;
        cin>>a>>b;

        s.insert({a,b});
    }

    int ans = 0;

    while(s.size()>1)
    {
        auto it = s.begin();
        int y = it->second;
        s.erase(s.begin());
        ans++;

        

        while(1)
        {
            auto it = s.lower_bound({y,0});
            if(it==s.end()) break;
            int y = it->second;
            s.erase(it);
        }
    }

    cout<<ans<<endl;
}


signed main()
{
    IOS
    //int _t;cin>>_t;while(_t--)
    solver();
    return 0;
}

#undef int