N,V=map(int,raw_input().split())
C=map(int,raw_input().split())
s=0
S=[]
A=[]
for i in range(N):
    s+=C[i]
    S.append(s)
    A.append((s/(1.0+i),i))
A.sort()

m=A[0][1]+1

dp=[m*N*1000000000 for i in range(m*N+1)]
dp[0]=0
for i in range(N):
    for j in range(m*N+1):
        if i+j+1 >=m*N+1:
            continue
        dp[i+j+1]=min(dp[i+j+1],dp[j]+S[i])

v = V-N
t = max(0, (v-m*N+m-1)/m)
print s+t*S[A[0][1]]+dp[max(0,v-t*m)]