import numpy as np
N,V=map(int,input().split())
C=np.array([*map(int,input().split())]).cumsum()
X=C[-1];V-=N
if V<0:exit(print(X))
m=np.argmin(C/[*range(1,N+1)])+1
d=V-N*N
if d>0:X+=d//m*C[m-1];V=d%m+N*N
dp=np.array([0]+[1<<60]*V)
for i in range(1,N+1):
 for j in range(i,V+1):dp[j]=min(dp[j],dp[j-i]+C[i-1])
print(X+dp[V])