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

// ================== MACROS ==================
#define ll long long
#define ull unsigned long long
#define ld long double
#define endl '\n'
#define str string
#define ld long double
#define vld vector<ld>
#define vi vector<int>
#define vb vector<bool>
#define vstr vector<str>
#define umapii unordered_map<int, int>
#define vvi vector<vi>
#define vll vector<ll>
#define pii pair<int, int>
#define pll pair<ll, ll>
#define vpii vector<pair<int, int>>
#define i128 __int128_t
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define pb push_back
#define ff first
#define ss second

// ================== CONSTANTS ==================
const ll INF = 1e18;
// const int MOD = 1e9 + 7;  // leetcode
const int MOD = 998244353;  // atcoder, codeforces
// const int MOD = 1001113;  // kattis
const int N = 2e5 + 5;
string v = "aeiou";
string V = "AEIOU";

// ================== MATH ==================
ll gcd(ll a, ll b) { return b ? gcd(b, a % b) : a; }
ll lcm(ll a, ll b) { return a / gcd(a, b) * b; }

ll mod_add(ll a, ll b) { return (a % MOD + b % MOD) % MOD; }
ll mod_mul(ll a, ll b) { return (a % MOD * b % MOD) % MOD; }
ll mod_pow(ll a, ll b) {
  ll res = 1;
  while (b) {
    if (b & 1) res = mod_mul(res, a);
    a = mod_mul(a, a);
    b >>= 1;
  }
  return res;
}

// ================== SOLUTION ==================
void solve() {
  int n;
  cin >> n;

  unordered_map<int, int> mp;

  while (n--) {
    int s, t;
    cin >> s >> t;

    if (mp.count(s) && mp[s] != t) {
      cout << "No\n";
      return;
    }

    mp[s] = t;
  }

  cout << "Yes\n";
}

int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);

  int t = 1;
  // cin >> t;
  while (t--) {
    solve();
  }

  return 0;
}