#include <bits/stdc++.h>
using namespace std;

using ll = long long;
#define rep(i, n) for(int i = 0; i < n; i++)

int main() {
	int N;
	cin >> N;
	using P = pair<int, int>;
	set<P> st;
	rep(i, N) {
		int a, b;
		cin >> a >> b;
		P p = P(a, b);
		if(st.count(p)) {
			cout << "Yes" << endl;
			return 0;
		}
		st.insert(p);
	}
	cout << "No" << endl;
}