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

int main()
{
    int n; cin >> n;
    vector < pair <int, int> > A(n);
    for(int i = 0; i < n; i++){
        cin >> A[i].first >> A[i].second;
    }
    sort(A.begin(), A.end());
    vector <int> G;
    for(int i = 0; i < n; i++){
        bool found = false;
        for(int j = 0; j < G.size(); j++){
            if(G[j] == A[i].first){
                found = true;
                G[j] = A[i].second;
                break;
            }
        }
        if(!found) G.push_back(A[i].second);
    }
    cout << G.size() << '\n';
    return 0;
}