#include <iostream>
#include <vector>
using namespace std ;
using ll = long long ;
int main(int argc, char *argv[]) {
   int n ;
   cin >> n ;
   vector<ll> v(n) ;
   for (auto &vv: v)
      cin >> vv ;
   int r = -1 ;
   for (int i=1; i+1<(int)v.size(); i++)
      if (v[i-1] == v[i+1] && v[i] > v[i-1] && v[i] > v[i+1]) {
         int len = 2 ;
         while (i >= len && i+len < (int)v.size() && v[i-len] == v[i+len] && v[i-len] < v[i-len+1])
            len++ ;
         r = max(r, 2 * len - 1) ;
      }
   cout << r << endl ;
}