#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
using namespace std;
const long long int mod = 1e9 + 7;
const long long int mod1 = 998244353;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
long long int rand(long long int l, long long int r) {
  uniform_int_distribution<long long int> uid(l, r);
  return uid(rng);
}
const long long int N = 2e5 + 5;
vector<pair<long long int, long long int> > v;
long long int dsu[N], sz[N], a[N];
bool active[N];
long long int odd = 0;
long long int root(long long int u) {
  return (dsu[u] == u) ? u : (dsu[u] = root(dsu[u]));
}
long long int n;
void uni(long long int u, long long int v) {
  if (u < 1 || u > n) return;
  u = root(u), v = root(v);
  if (u == v) return;
  odd -= (sz[u] & 1);
  odd -= (sz[v] & 1);
  sz[v] += sz[u];
  odd += (sz[v] & 1);
  dsu[u] = v;
}
void solve() {
  cin >> n;
  for (long long int i = 1; i <= n; i++) dsu[i] = i, sz[i] = 1;
  for (long long int i = 1; i <= n; i++) cin >> a[i], v.push_back({a[i], i});
  sort(v.begin(), v.end());
  long long int pt = 0;
  while (1) {
    long long int val = v[pt].first;
    while (pt < n && v[pt].first == val) {
      active[v[pt].second] = 1;
      odd++;
      if (active[v[pt].second - 1]) {
        uni(v[pt].second - 1, v[pt].second);
      }
      if (active[v[pt].second + 1]) {
        uni(v[pt].second, v[pt].second + 1);
      }
      pt++;
    }
    if (odd && pt != n) {
      cout << "NO" << '\n';
      return;
    }
    if (pt == n) break;
  }
  cout << "YES" << '\n';
}
signed main() {
  ios ::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  clock_t clk = clock();
  long long int t = 1;
  while (t--) {
    solve();
  }
  cerr << '\n' << (double)(clock() - clk) / CLOCKS_PER_SEC;
  return 0;
}
