import itertools
import sys
import fractions

input = sys.stdin.readline


def main():
    N, V = map(int, input().split())
    *C, = itertools.accumulate(map(int, input().split()))

    V -= N
    if V <= 0:
        print(C[-1])
        return

    L = (N**3-N)//2
    DP = [0] + [float('inf')]*L

    for i in range(1, L+1):
        for j in range(N):
            if i > j:
                DP[i] = min(DP[i], DP[i-(j+1)]+C[j])

    if V <= L:
        print(C[-1] + DP[V])
    else:
        target = min(range(N), key=lambda i: fractions.Fraction(C[i], i+1))
        greedy = (V-(L+1))//(target+1) + 1
        print(C[-1] + greedy*C[target] + DP[V-(target+1)*greedy])


if __name__ == '__main__':
    main()