#include <iostream>
#include <vector>
#include <set>
#include <map>
#include <algorithm>
#include <iomanip>
#include <numeric>
using namespace std;
using ll = long long;
int main() {
	int N;cin >> N;
	vector<int> A(N);
	for (int i = 0;i < N;i++) cin >> A[i];
	for (int i = 0;i < N-1;i++) {
		vector<int> B = A;
		swap(B[i], B[i+1]);
		int c = 0;
		for (int t = 0;t < N-1;t++) if (B[t] == B[t+1]) c++;
		if (c >= 1) {
			cout <<"Yes" << endl;
			return 0;
		}
	}
	cout <<"No" << endl;
}