#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i, s, t) for (ll i = s; i < (ll)(t); i++)
#define rrep(i, s, t) for(ll i = (ll)(t) - 1; i >= (ll)(s); i--)
#define all(x) begin(x), end(x)
#define rall(x) rbegin(x), rend(x)

#define TT template<typename T>
TT using vec = vector<T>;
template<class T1, class T2> bool chmin(T1 &x, T2 y) { return x > y ? (x = y, true) : false; }
template<class T1, class T2> bool chmax(T1 &x, T2 y) { return x < y ? (x = y, true) : false; }

struct io_setup {
    io_setup() {
        ios::sync_with_stdio(false);
        std::cin.tie(nullptr);
        cout << fixed << setprecision(15);
    }
} io_setup;

void solve(){
    int N;
    cin>>N;
    vector<string>S(N),T(N);
    map<string,int>mp;
    rep(i,0,N){
        cin>>S[i]>>T[i];
        mp[S[i]]++;
        mp[T[i]]++;
    }
    rep(i,0,N){
        if(mp[S[i]]>1&&mp[T[i]]>1){
            cout<<"No\n";
            return;
        }
    }
    cout<<"Yes\n";
}

int main() {
    solve();
}