def P_3799():
    """
    https://www.luogu.com.cn/problem/P3799
    Returns:

    """
    N = int(input().strip())
    num_list = [0 for _ in range(5010)]
    ans = 0
    max_n = 100000000 + 7

    for i in range(N):
        wood_length = int(input().strip())
        num_list[wood_length] += 1

    for i in range(2, 5001):
        if num_list[i] >= 2:
            for j in range(1, i // 2 + 1):
                if num_list[j] >= 1 and num_list[i - j] >= 1 and j < i - j:
                    ans += (num_list[i] * (num_list[i] - 1) * num_list[j] * num_list[i - j] // 2) % max_n
                elif j == i - j and num_list[j] >= 2:
                    ans += (num_list[i] * (num_list[i] - 1) * num_list[j] * (num_list[j] - 1) // 4) % max_n
                else:
                    pass
        ans %= max_n
    print(int(ans))