#include<bits/stdc++.h>
#include<atcoder/all>

using namespace std;

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++) {
       auto a = A;
       swap(a[i], a[i+1]);
       for (int j=0;j<N-1;j++) {
           if (a[j]==a[j+1]) {
               cout << "Yes" << endl;
               return 0;
           }
       }
   }
   cout << "No" << endl;
   return 0;
}