Codeforces 439 A. Devu, the Singer and Churu, the Joker

 这是本人第一次写代码，难免有点瑕疵还请见谅                                                                                          

A. Devu, the Singer and Churu, the Joker

time limit per test

 1 second

memory limit per test

 256 megabytes

input

 standard input

output

 standard output

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.

Sample test(s)

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.

 

 

关于这题的解题报告：本人觉得当你想多了的时候就会把太多的时间浪费掉了，因为本人就体验过，算了发了一下牢骚就打住吧；

对于这题：基本思路就是简单的模拟；

下面就是本人的代码：

#include<cstdio>
#define N 100

int t[N];
int main()
{
    int d,n;
    int Sum = 0;
    int count = 0;
    
    scanf("%d%d",&n,&d);
    for(int i=1;i<=n;++i){
        scanf("%d",&t[i]);
        Sum += t[i];
    }
    Sum += (n-1)*10;
    if(Sum > d)
         printf("-1\n");
    else
    {
        count += (n-1)*2;
        printf("%d\n",count+(d-Sum)/5);
    }
    int a;scanf("%d\n",&a);
    return 0;
}