def solve(N, V, C):
    A = [0] * N
    A[0] = C[0]

    for i in range(1, N):
        A[i] = A[i - 1] + C[i]

    R = [(a / (i + 1), i) for i, a in enumerate(A)]
    R.sort()

    L = [0] * N
    L[N - 1] = 1

    cost = sum(C)

    V -= N

    if V <= 0:
        return cost

    r0 = R[0][1]

    d = V // (r0 + 1)
    d -= r0

    v = V - d * (r0 + 1)
    cost += A[r0] * d

    DP = [2 ** 63] * (v + 1)
    DP[0] = 0

    for i in range(v):
        for j in range(r0 + 1):
            if i + j + 1 <= v:
                DP[i + j + 1] = min(DP[i + j + 1], DP[i] + A[j])

    return DP[v] + cost


def main():
    N, V = list(map(int, input().split()))
    C = list(map(int, input().split()))
    print(solve(N, V, C))


if __name__ == '__main__':
    main()