#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
const long long mod=998244353;
const long long mod100=1000000007;
int main(){
    cin.tie(0)->sync_with_stdio(0);
    cout.tie(0);
    int N;
    cin>>N;
    int A[N+2];
    for(int i=1;i<=N;i++) cin>>A[i];
    A[0]=-1;
    A[N+1]=-1;
    for(int i=1;i<N;i++){
        swap(A[i],A[i+1]);
        if(A[i]==A[i-1] || A[i]==A[i+1] || A[i+1]==A[i+2]){
            cout<<"Yes\n";
            return 0;
        }
        swap(A[i],A[i+1]);
    }
    cout<<"No\n";
}