#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }
ll inf_ll = 9223372036854775807;
#define rep(i, n) for (ll i = 0; i < (ll)(n); i++)
using mint = atcoder::modint998244353;
using mint1 = atcoder::modint1000000007;
using Pa = std::pair<ll, ll>;

int Yes(bool x){
    if(x) cout << "Yes";
    else cout << "No";
    cout << endl;
    return 0;
}

int main(){
    ll N;
    cin >> N;
   vector<string> A(N), B(N);
    rep(i, N){
        cin >> A[i] >> B[i];
    }
    bool ans = true;
    rep(i, N){
        bool a = true, b = true;
        rep(j, N){
            if(i == j) continue;
            if(A[i] == A[j] || A[i] == B[j]) a = false;
            if(B[i] == B[j] || B[i] == A[j]) b = false;
        }
        if(!a && !b) ans = false;
    }
    Yes(ans);
}