#include <bits/stdc++.h>
#define int long long
#define x first
#define y second
#define pb push_back
void debug() {std::cerr << "\n";}
template<class T, class... OtherArgs>
void debug(T &&var, OtherArgs &&... args) {
    std::cerr << std::forward<T>(var) << " ";
    debug(std::forward<OtherArgs>(args)...);
}
#define SZ(x) (int)(x).size()
#define all(x) (x).begin(), (x).end()
using namespace std;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
typedef long long LL;
typedef long double LD;
typedef unsigned long long ULL;
typedef pair<int, int> PII;
const int N = 1010, M = 10000010;
const int P = 998244353;
LL powmod(LL a, LL b, LL p = P) {LL res = 1 % p; a %= p; assert(b >= 0); for(; b; b >>= 1) { if (b & 1) res = res * a % p; a = a * a % p; } return res; }

int n, m;
__int128 dp[N][N], a[N];

void read(__int128 &n){
    __int128 x = 0, f = 1;
    char ch = getchar();
    while (ch < '0' || ch > '9') {
        if (ch == '-') f = -1;
        ch = getchar();
    }
    while (ch >= '0' && ch <= '9') {
        x = (x << 1) + (x << 3) + (ch ^ 48);
        ch = getchar();
    }
    n = x * f;
}

void print(__int128 n){
    if (n < 0) {
        putchar('-');
        n = -n;
    }
    if (n > 9) {
        print(n / 10);
    }
    putchar(n % 10 + '0');
}

void solve() {
    cin >> n;
    for (int i = 1; i <= n; i++) {
        read(a[i]);
        dp[i][i] = a[i];
    }

    for (int len = 2; len <= n; len++) {
        for (int l = 1; l + len - 1 <= n; l++) {
            int r = l + len - 1;
            if (a[l] == dp[l + 1][r]) {
                dp[l][r] = max(dp[l][r], dp[l + 1][r] * 2);
            } else {
                dp[l][r] = max(dp[l][r], max(dp[l + 1][r], a[l]));
            }
            if (a[r] == dp[l][r - 1]) {
                dp[l][r] = max(dp[l][r], dp[l][r - 1] * 2);
            } else {
                dp[l][r] = max(dp[l][r], max(dp[l][r - 1], a[r]));
            }
        }
    }
    print(dp[1][n]);
}

signed main() {
    // ios::sync_with_stdio(false);
    // cin.tie(nullptr);
    // cout << fixed << setprecision(20);
    int _ = 1;
    // cin >> _;
    while (_--) solve();
}