import sys
input = lambda : sys.stdin.readline().rstrip()

sys.setrecursionlimit(2*10**5+10)
write = lambda x: sys.stdout.write(x+"\n")
debug = lambda x: sys.stderr.write(x+"\n")
writef = lambda x: print("{:.12f}".format(x))


n,m = list(map(int, input().split()))
a = list(map(int, input().split()))
a.sort(reverse=1)
dp = [[0]*(m+1) for _ in range(n+1)]
def chmax(i,j,v):
    dp[i][j] = max(dp[i][j], v)
for i in range(n):
    for j in range(m+1):
        v = dp[i][j]
        if i+2<=n:
            nj = j+a[i]-a[i+1]
            if nj<=m:
                chmax(i+2, nj, v+a[i])
        chmax(i+1,j, v)
ans = max(dp[n])
print(ans)