#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
#define X first
#define Y second
#define ALL(v) v.begin(), v.end()
#define pb push_back
#define SZ(a) ((int)a.size())

int main() {
    ios::sync_with_stdio(0), cin.tie(0);
    int n;
    cin >> n;
    vector<int> arr(n);
    for (int &i : arr)
        cin >> i;
    int ans = -1;
    for (int i = 1; i + 1 < n; ++i) {
        if (arr[i] > arr[i - 1] && arr[i] > arr[i + 1] && arr[i - 1] == arr[i + 1]) {
            int cur = 3, lst = arr[i - 1];
            for (int j = 2; i - j >= 0 && i + j < n; ++j)
                if (arr[i - j] == arr[i + j] && lst > arr[i - j]) {
                    lst = arr[i - j];
                    cur += 2;
                }
                else
                    break;
            ans = max(ans, cur);
        }
    }
    cout << ans << "\n";
}