#include <bits/stdc++.h>
//#include <atcoder/modint>

using namespace std;
//using namespace atcoder;
using ll = long long;
//using mint = modint998244353;

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

    int N;
    cin >> N;
    map<string, int> mp;
    vector<string> s(N), t(N);
    for (int i=0; i<N; i++){
        cin >> s[i] >> t[i];
        mp[s[i]]++;
        mp[t[i]]++;
    }
    for (int i=0; i<N; i++){
        mp[s[i]]--;
        mp[t[i]]--;
        if (mp[s[i]] != 0 && mp[t[i]] != 0){
            cout << "No" << endl;
            return 0;
        }
        mp[s[i]]++;
        mp[t[i]]++;
    }

    cout << "Yes" << endl;

    return 0;
}