#include <bits/stdc++.h>
using namespace std;
template <class T>
T maxT(T a, T b) {
  return (a > b ? a : b);
}
template <class T>
T minT(T a, T b) {
  return (a < b ? a : b);
}
template <class T>
void setmin(T &a, T b) {
  a = (a > b ? a : b);
}
template <class T>
void setmax(T &a, T b) {
  a = (a < b ? a : b);
}
void fileio() {
  freopen("input.txt", "r", stdin);
  freopen("output.txt", "w", stdout);
  freopen("debug.txt", "w", stderr);
}
void ofileio() {
  freopen("input.txt", "r", stdin);
  freopen("output.txt", "w", stdout);
}
void clock_out() {
  cerr << "\nTime Elapsed : " << 1.0 * clock() / CLOCKS_PER_SEC << " s\n";
}
void debug_out() { cerr << endl; }
template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
  cerr << " " << H;
  debug_out(T...);
}
const long long MOD = 1000000007;
const long long SIZE = 100000;
const int INF = 0x3f3f3f3f;
const long long LL_INF = 0x3f3f3f3f3f3f3f3f;
const long double PI = acos(-1);
const long long MAXN = numeric_limits<long long>::max();
void solve() {
  int n;
  cin >> n;
  vector<int> a(n);
  int cnt = 1;
  vector<int> b;
  for (long long i = 0; i < n; i++) {
    cin >> a[i];
    if (i) {
      if (a[i] == a[i - 1]) {
        cnt++;
      } else {
        b.push_back(cnt);
        cnt = 1;
      }
    }
  }
  b.push_back(cnt);
  for (int i = 1; i < b.size(); i++) {
    if (b[i] != b[i - 1]) {
      cout << "NO\n";
      return;
    }
  }
  cout << "YES\n";
}
int main() {
  ios_base::sync_with_stdio(false), cin.tie(0), cout.tie(0);
  srand(time(NULL));
  1;
  long long t = 1;
  while (t--) {
    solve();
  }
  1;
  return 0;
}
