#include <stdio.h>
#include <atcoder/all>
#include <bits/stdc++.h>
using namespace std;
using namespace atcoder;
using mint = modint998244353;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf32 1000000005
#define Inf64 4000000000000000001LL

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