439_A. Devu, the Singer and Churu, the Joker
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 the second example. There is no way of organizing Devu's all songs. Hence the answer is -1. 
```python
a,b=input().split()
a=int(a)
b=int(b)
clist=list(map(int,input().split()))
sumi=sum(clist)
d=b-sumi
if(d>=(a-1)*10):
    print(d//5)
else:
    print("-1")
```