#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (n); ++i)
using ll = long long;
using ull = unsigned long long;

int main() {
  cin.tie(nullptr)->sync_with_stdio(false);
  int n;
  cin >> n;
  vector<int> a(n);
  rep(i, n) cin >> a[i];
  bool ans = false;
  rep(i, n - 1) ans |= a[i] == a[i + 1];
  rep(i, n - 1) {
    swap(a[i], a[i + 1]);
    if (i > 0) ans |= a[i - 1] == a[i];
    if (i + 2 < n) ans |= a[i + 1] == a[i + 2];
    swap(a[i], a[i + 1]);
  }
  cout << (ans ? "Yes" : "No") << '\n';
  return 0;
}