#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  vector<int> a(n);
  set<int> q;
  for (int i = 0; i < n; i++) {
    cin >> a[i];
  }
  int cnt = 1;
  for (int i = 1; i < n; i++) {
    if (a[i] == a[i - 1])
      cnt++;
    else
      q.insert(cnt), cnt = 1;
  }
  q.insert(cnt);
  if (q.size() == 1)
    cout << "YES";
  else
    cout << "NO";
}
