#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
#define ll long long
#define rep(i,a,b) for(int i=(a);i<(b);i++)
#define repl(i,a,b) for(ll i=(a);i<(b);i++)
#define all(a) (a).begin(),(a).end()

template <typename T> bool chmin(T &a,T b){if(a>b){a=b;return true;} return false;}
template <typename T> bool chmax(T &a,T b){if(a<b){a=b;return true;} return false;}

int main(){
  int n; cin >> n;
  vector<string> s(n),t(n);
  rep(i,0,n) cin >> s[i] >> t[i];
  bool can=true;
  rep(i,0,n){
    bool ch1=true;
    rep(j,0,n){
      if(i == j) continue;
      if((s[i] == s[j] || s[i] == t[j])) ch1=false;
    }
    bool ch2=true;
    rep(j,0,n){
      if(i == j) continue;
      if((t[i] == s[j] || t[i] == t[j])) ch2=false;
    }
    if(!ch1 && !ch2) can=false;
  }
  if(can) cout << "Yes" << endl;
  else cout << "No" << endl;
}