import sys
input=lambda:sys.stdin.readline().rstrip()
N,V=map(int,input().split())
C=list(map(int,input().split()))
for i in range(N-1):
	C[i+1]+=C[i]
if V<=N:
	print(C[N-1])
	sys.exit()
temp=[C[i]/(i+1) for i in range(N)]
k=temp.index(min(temp))
chunks=max((V-N**2)//(k+1),0)
ans=C[N-1]+chunks*C[k]
V-=N+chunks*(k+1)
dp=[[float('inf') for i in range(V+1)] for j in range(N)]
dp[0]=[C[0]*i for i in range(V+1)]
for i in range(1,N):
	for j in range(i+1):
		for k in range(j//(i+1)+1):
			dp[i][j]=min(dp[i][j],dp[i-1][j-k*(i+1)]+k*C[i])
	for j in range(i+1,V+1):
		dp[i][j]=min(dp[i][j-(i+1)]+C[i],dp[i-1][j])
print(ans+dp[N-1][V])