#include <bits/stdc++.h>
using namespace std;

#define rep(i, a, b) for (int i = a; i < b; i++)
using ll = long long;

int main() {
	int n;
	cin >> n;
	vector<int> a(n);
	rep(i, 0, n) cin >> a[i];
	string ans =  "No";
	rep(i, 0, n - 2) {
		if (a[i]  == a[i + 2]) {
			swap(a[i], a[i + 1]);
			break;
		}
	}
	rep(i, 0, n - 1) {
		if(a[i] == a[i + 1]) {
			ans = "Yes";
			break;
		}
	}
	cout << ans << endl;
}