#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef pair<ll,ll> P;
#define REP(i,n) for(ll i=0;i<ll(n);i++)













int main(void){
	cin.tie(nullptr);  ios_base::sync_with_stdio(false);
	ll i,j;




	ll N;
	cin >> N;

	if(N==0){
		cout << "Yes" << endl;
		return 0;
	}


	map<ll,vector<ll>> m;
	for(i=1;i<=N;i++){
		ll s,t;
		cin >> s >> t;

		m[s].push_back(t);
	}


	for(auto c:m){

		vector<ll> v=c.second;

		sort(v.begin(),v.end());
		v.erase(unique(v.begin(),v.end()),v.end());

		if((ll)v.size()!=1){
			cout << "No" << endl;
			return 0;
		}


	}


	cout << "Yes" << endl;






	return 0;

}