human
Can you provide a Python program to find a way to conduct all the songs of the Devu, output -1 given the following:
Devu is a renowned classical singer. He is invited to many big functions/festivals. Recently he was invited to "All World Classical Singing Festival". Other than Devu, comedian Churu was also invited.

Devu has provided organizers a list of the songs and required time for singing them. He will sing n songs, ith song will take ti minutes exactly. 

The Comedian, Churu will crack jokes. All his jokes are of 5 minutes exactly.

People have mainly come to listen Devu. But you know that he needs rest of 10 minutes after each song. On the other hand, Churu being a very active person, doesn't need any rest.

You as one of the organizers should make an optimal sсhedule for the event. For some reasons you must follow the conditions:

  * The duration of the event must be no more than d minutes.

  * Devu must complete all his songs.

  * With satisfying the two previous conditions the number of jokes cracked by Churu should be as many as possible. 


If it is not possible to find a way to conduct all the songs of the Devu, output -1. Otherwise find out maximum number of jokes that Churu can crack in the grand event.

Input

The first line contains two space separated integers n, d (1 ≤ n ≤ 100.
1 ≤ d ≤ 10000). The second line contains n space-separated integers: t1, t2, ..., tn (1 ≤ ti ≤ 100).

Output

If there is no way to conduct all the songs of Devu, output -1. Otherwise output the maximum number of jokes that Churu can crack in the grand event.

Examples

Input

3 30
2 2 1

Output

5

Input

3 20
2 1 1

Output

-1

Note

Consider the first example. The duration of the event is 30 minutes. There could be maximum 5 jokes in the following way:

  * First Churu cracks a joke in 5 minutes. 
  * Then Devu performs the first song for 2 minutes. 
  * Then Churu cracks 2 jokes in 10 minutes. 
  * Now Devu performs second song for 2 minutes. 
  * Then Churu cracks 2 jokes in 10 minutes. 
  * Now finally Devu will perform his last song in 1 minutes. 


Total time spent is 5 + 2 + 10 + 2 + 10 + 1 = 30 minutes.

Consider...
#.*?\
assistant
#Here is Python program to find a way to conduct all the songs of the Devu, output -1.
n
#from collections import Counter
#from collections import defaultdict
#from collections import deque

# BIT_MANIPULATION
# def intToBin(num:int): return "{0:b}".format(num)
# def binToInt(bin:str)->int: return int(bin,2)

# INPUT
def inpNum(): return int(input())
def inpNums(): return map(int,input().split())
def inpList(): return list(map(int,input().split()))
# def inpMatrix(rows): return [list(map(int, input().split())) for _ in range(rows)]

# problem code:

n,d = inpNums()
ni = inpList()
ttl = sum(ni)
tttl= ttl + (len(ni)-1)*10

if tttl > d: print(-1)
else:
    tttl = d-ttl
    print(tttl//5)