Devu, the Singer and Churu, the Joker

Description

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, i^th song will take t_i 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, ..., t_n(1 ≤ t_i ≤ 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.

Sample Input

Input

3 30
2 2 1

Output

5

Input

3 20
2 1 1

Output

-1

Hint

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.

#include<iostream>
#include<algorithm>
using namespace std;

int main(){
    int n,d,jokes,t,time,temp,flag;
    int songtime[110];
    while(cin>>n>>d){
        flag=1;
        time=0;
        jokes=0;
        for(int i=0;i<n;i++){
            cin>>t;
            time+=(t+10);
            jokes+=2;
        }
        time-=10;
        jokes-=2;
        if(time>d){
            flag=0;
        }
        else{
            temp=d-time;
            jokes+=(temp/5);
        }
        if(flag==1){
            cout<<jokes<<endl;
        }
        else{
            cout<<"-1"<<endl;
        }
    }
    return 0;
}