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, m):
    d = Ds[m]
    dp = get_dp(N, Ds, m)
    # V - N * m <= i * (m + 1) <= V    
    ibegin = max(0, 1 + (V - N * m - 1) // (m + 1))
    iend = 1 + V // (m + 1)
    return min(d * i + dp[V - (m + 1) * i] for i in range(ibegin, iend))


def get_dp(N, Ds, m):
    dp = [0] + [float('inf')] * (N * m)
    for i in range(1, N * m + 1):
        dp[i] = min(dp[i - j] + d for j, d in enumerate(Ds[:i], 1))
    return dp

if __name__ == '__main__':
    N, V, Cs = read_data()
    print(solve(N, V, Cs))