Problem:
Score : 100 points

Problem Statement

There are N slimes lining up in a row.
Initially, the i-th slime from the left has a size of a_i.

Taro is trying to combine all the slimes into a larger slime.
He will perform the following operation repeatedly until there is only one slime:

Choose two adjacent slimes, and combine them into a new slime. The new slime has a size of x + y, where x and y are the sizes of the slimes before combining them. Here, a cost of x + y is incurred. The positional relationship of the slimes does not change while combining slimes.

Find the minimum possible total cost incurred.

Constraints

All values in input are integers.

2 \leq N \leq 400

1 \leq a_i \leq 10^9

Input

Input is given from Standard Input in the following format:

N
a_1 a_2 \ldots a_N

Output

Print the minimum possible total cost incurred.

Sample Input 1

4
10 20 30 40

Sample Output 1

190

Taro should do as follows (slimes being combined are shown in bold):

(10, 20, 30, 40) → (30, 30, 40)

(30, 30, 40) → (60, 40)

(60, 40) → (100)

Sample Input 2

5
10 10 10 10 10

Sample Output 2

120

Taro should do, for example, as follows:

(10, 10, 10, 10, 10) → (20, 10, 10, 10)

(20, 10, 10, 10) → (20, 20, 10)

(20, 20, 10) → (20, 30)

(20, 30) → (50)

Sample Input 3

3
1000000000 1000000000 1000000000

Sample Output 3

5000000000

The answer may not fit into a 32-bit integer type.

Sample Input 4

6
7 6 8 6 1 1

Sample Output 4

68

Taro should do, for example, as follows:

(7, 6, 8, 6, 1, 1) → (7, 6, 8, 6, 2)

(7, 6, 8, 6, 2) → (7, 6, 8, 8)

(7, 6, 8, 8) → (13, 8, 8)

(13, 8, 8) → (13, 16)

(13, 16) → (29)

Solution in Java8 (OpenJDK 1.8.0) (judge verdict: Accepted)

import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long INF = 1_000_000_000_000_000_000L;
        int N = sc.nextInt();
        int[] a = new int[N];
        long[] ruiseki = new long[N+1];
        for (int i=0;i<N;i++) {
            a[i] = sc.nextInt();
            ruiseki[i+1] = ruiseki[i]+a[i];
        }

        long[][] dp = new long[N+1][N+1];
        for (int w=1;w<=N;w++) {
            for (int l=0;l<N;l++) {
                int r = l+w;
                if (r>N) continue;
                if (r==l+1) {
                    dp[l][r] = 0;
                } else {
                    long tmp = INF;
                    for (int mid=l+1;mid<r;mid++) {
                        tmp = Math.min(tmp, dp[l][mid]+dp[mid][r]+ruiseki[r]-ruiseki[l]);
                    }
                    dp[l][r] = tmp;
                }
            }
        }
        System.out.println(dp[0][N]);
    }
}