import itertools


def read_data():
    N, V = map(int, input().split())
    Cs = list(map(int, input().split()))
    return N, V, Cs


def select_most_efficient(Ds):
    n = 0
    cost = 1
    record = None
    for k, d in enumerate(Ds, 1):
        det = k * cost - n * d
        if det > 0:
            n = k
            cost = d
            record = k - 1
    return record


def solve(N, V, Cs):
    if V <= N:
        return sum(Cs)
    if N == 1:
        return Cs[0] * V
    V -= N
    Ds = list(itertools.accumulate(Cs))
    eff = select_most_efficient(Ds)
    return calc_cost(N, V, Cs, Ds, eff) + sum(Cs)


def calc_cost(N, V, Cs, Ds, idx):
    d = Ds[idx]
    m, r = divmod(V, idx + 1)
    if r == 0:
        return d * m
    dp = get_dp(N, Ds, idx)
    # V <= istart * (idx + 1) + N * idx
    i0 = max(0, 1 + (V - N * idx - 1) // (idx + 1))
    return min(d * i + dp[V - (idx + 1) * i] for i in range(i0, m + 1))


def get_dp(N, Ds, m):
    '''コスト Ds[i], 容量 i　のアイテムについて、
    dp[k][n][v] k 番目までのアイテムを 合計 n 個使ったときに、容量を v とする最小コストの値
    dp[k][n][v] = min(dp[k - 1][n][v], dp[k][n - 1][v - i] + Ds[i])
    '''
    dp = [[float('inf')] * (N * i + 1) for i in range(m + 1)]
    dp[0][0] = 0
    for i, d in enumerate(Ds, 1):
        for n, (dp_n, prev_dp) in enumerate(zip(dp[1:], dp[:-1]), 1):
            for v in range(i, i * n + 1):
                dp_n[v] = min(dp_n[v], prev_dp[v - i] + d)
    dp_min = dp[m]
    for dp_n in dp:
        for i, dp_ni in enumerate(dp_n):
            dp_min[i] = min(dp_min[i], dp_ni)
    return dp_min

N, V, Cs = read_data()
print(solve(N, V, Cs))