#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<long long> VL;
typedef vector<VL> VVL;
typedef long long LL;
#define all(a) (a).begin(), (a).end()
#define Yes(n) cout << ((n) ? "Yes" : "No"  ) << endl
#define YES(n) cout << ((n) ? "YES" : "NO"  ) << endl
#define ALL(a)  (a).begin(),(a).end()
#define pb push_back

int main() {
  int n;cin>>n;
  set<VI> D;
  rep(i,n){
    int a,b;cin>>a>>b;
    VI z={a,b};
    if(D.count(z)){Yes(1);return 0;}
    D.insert(z);
  }
  Yes(0);
}