#include "atcoder/modint.hpp"
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;

using i32 = int;
using i64 = long long;
using u64 = unsigned long long;
using i128 = __int128_t;
using f64 = long double;
using p2 = pair<i64, i64>;
using el = tuple<i64, i64, i64>;
using mint = atcoder::modint1000000007;

void _main();
int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  _main();
}

i64 pow(i64 x, i64 n, i64 m) {
  i64 res = 1;
  i64 t = x % m;
  while (n > 0) {
    if (n & 1) {
      res = res * t % m;
    }
    t = t * t % m;
    n >>= 1;
  }
  return res;
}

void _main() {
  i64 n;
  cin >> n;
  vector<string> s(n), t(n);
  map<string, i64> mp;
  for (i64 i = 0; i < n; i++) {
    cin >> s[i] >> t[i];
    mp[s[i]]++;
    mp[t[i]]++;
  }
  for (i64 i = 0; i < n; i++) {
    if (s[i] == t[i]) {
      if (mp[s[i]] > 2) {
        cout << "No\n";
        return;
      }
    } else if (mp[s[i]] > 1 && mp[t[i]] > 1) {
      cout << "No\n";
      return;
    }
  }
  cout << "Yes\n";
}