#include<bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0;i<(int)(n);++i)
int N;
string S[100],T[100];
signed main(){
  cin.tie(0)->sync_with_stdio(0);
  cin>>N;
  rep(i,N)cin>>S[i]>>T[i];
  rep(i,N){
    bool ok=1;
    rep(j,N){
      if(i==j)continue;
      if(S[i]==S[j]||S[i]==T[j])ok=0;
    }
    if(ok)continue;
    rep(j,N){
      if(i==j)continue;
      if(T[i]==S[j]||T[i]==T[j]){
        cout<<"No\n";
        return 0;
      }
    }
  }
  cout<<"Yes\n";
}