#include <bits/stdc++.h>
using namespace std;
mt19937 rnd(51);
signed main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  long long n;
  cin >> n;
  vector<long long> a(n);
  for (long long i = 0; i < n; i++) {
    cin >> a[i];
  }
  deque<pair<long long, long long>> q;
  for (long long i = 0; i < n; i++) {
    if (q.size() == 0) {
      q.push_back({a[i], 1});
    } else {
      if (q.back().first == a[i]) {
        q.back().second++;
        if (q.size() > 1 && q[q.size() - 2].first >= q.back().first) {
          long long now = q.back().second;
          q.pop_back();
          q.back().second += now;
        }
      } else if (q.back().first > a[i]) {
        q.push_back({a[i], 1});
      } else {
        if (q.back().second % 2 == 1) {
          cout << "NO\n";
          return 0;
        } else {
          q.push_back({a[i], 1});
        }
      }
    }
  }
  while (q.size() > 1 && ((q[q.size() - 2].second % 2 == 0 &&
                           q[q.size() - 2].first < q.back().first) ||
                          (q.back().second % 2 == 0 &&
                           q.back().first < q[q.size() - 2].first))) {
    long long now = q.back().second;
    long long mx = max(q.back().first, q[q.size() - 2].first);
    q.pop_back();
    q.back().first = mx;
    q.back().second += now;
  }
  if (q.size() == 1) {
    cout << "YES\n";
  } else {
    cout << "NO\n";
  }
  return 0;
}
