//#define _GLIBCXX_DEBUG
#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (ll i = 0; i < (ll)(n); i++)
#define all(a) (a).begin(), (a).end()
using ll = long long;
const ll INF32 = 2e9;
const ll INF64 = 4e18;

void printYN(bool ok){
    if(ok)cout << "Yes" << endl;
    else cout << "No" << endl;
    return;
}

int main() {
    int N;
    cin >> N;
    set<pair<int, int>> st;
    bool ok = false;
    rep(i, N){
        int a, b;
        cin >> a >> b;
        if(st.count({a, b}))ok = true;
        st.insert({a,b});
    }
    printYN(ok);
    return 0;
}