备注：
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#include <queue>
#include <math.h>
#include <stack>
#include <stdio.h>
#include <iostream>
#include <vector>
#include <iomanip>
#include <string.h>
#include <algorithm>
#include <map>
using namespace std;
#define int long long
const int N = 1e3 + 10;
const int INF = 0x3f3f3f3f;
int n;
int a[N];
int dp[N][N][41];
void calc(int t[], int s)
{
int k = 0;
for(int i = 0; i < 40; i++)
{
t[i] = t[i] * s + k;
k = t[i] / 10;
t[i] %= 10;
}
}
void add(int t[], int dp[])
{
for(int i = 0; i < 40; i++)
{
t[i] += dp[i];
t[i+1] += t[i] / 10;
t[i] %= 10;
}
}
bool cmp(int t[], int dp[])
{
for(int i = 40; i >= 0; i--)
{
if(t[i] > dp[i])
return false;
else if(t[i] < dp[i])
return true;
}
return false;
}
void print(int dp[])
{
int k = 40;
while(dp[k] == 0)
k--;
for(int i = k; i >= 0; i--)
{
cout << dp[i];
}
cout << endl;
}
signed main()
{
//freopen(".in", "r", stdin);
//freopen(".out", "w", stdout);
cin >> n;
for(int i = 1; i <= n; i++)
{
cin >> a[i];
}
for(int k = 3; k <= n; k++)
{
for(int l = 1; l <= n-k+1; l++)
{
int r = l+k-1;
dp[l][r][40] = 1;
for(int i = l+1; i < r; i++)
{
int t[41];
memset(t, 0, sizeof(t));
t[0] = 1;
calc(t, a[i]);
calc(t, a[l]);
calc(t, a[r]);
add(t, dp[l][i]);
add(t, dp[i][r]);
if(cmp(t, dp[l][r]))
memcpy(dp[l][r], t, sizeof(t));
}
}
}
print(dp[1][n]);
return 0;
}