#include <iostream>
#include <set>
#include <map>
using namespace std;

int main(){
    int Q;
    cin >> Q;

    map<int, set<int>> M;
    while (Q--){
        int x, y;
        cin >> x >> y;
        M[x].insert(y);
    }

    bool ans = true;
    for (auto [_, s] : M){
        if (s.size() > 1){
            ans = false;
        }
    }
    cout << (ans? "Yes": "No") << endl;
}