第一次寫博客,一道水題,string game


D. String Game
time limit per test
2 seconds
memory limit per test
512 megabytes
input
standard input
output
standard output

Little Nastya has a hobby, she likes to remove some letters from word, to obtain another word. But it turns out to be pretty hard for her, because she is too young. Therefore, her brother Sergey always helps her.

Sergey gives Nastya the word t and wants to get the word p out of it. Nastya removes letters in a certain order (one after another, in this order strictly), which is specified by permutation of letters' indices of the word ta1... a|t|. We denote the length of word x as |x|. Note that after removing one letter, the indices of other letters don't change. For example, if t = "nastya" and a = [4, 1, 5, 3, 2, 6] then removals make the following sequence of words "nastya "nastya "nastya "nastya "nastya "nastya"nastya".

Sergey knows this permutation. His goal is to stop his sister at some point and continue removing by himself to get the word p. Since Nastya likes this activity, Sergey wants to stop her as late as possible. Your task is to determine, how many letters Nastya can remove before she will be stopped by Sergey.

It is guaranteed that the word p can be obtained by removing the letters from word t.

Input

The first and second lines of the input contain the words t and p, respectively. Words are composed of lowercase letters of the Latin alphabet (1 ≤ |p| < |t| ≤ 200 000). It is guaranteed that the word p can be obtained by removing the letters from word t.

Next line contains a permutation a1, a2, ..., a|t| of letter indices that specifies the order in which Nastya removes letters of t (1 ≤ ai ≤ |t|, all ai are distinct).

Output

Print a single integer number, the maximum number of letters that Nastya can remove.

Examples
input
ababcba
abb
5 3 4 1 7 6 2
output
3
input
bbbabb
bb
1 6 3 4 2 5
output
4
Note

In the first sample test sequence of removing made by Nastya looks like this:

"ababcba "ababcba "ababcba "ababcba"

Nastya can not continue, because it is impossible to get word "abb" from word "ababcba".

So, Nastya will remove only three letters.


由於題目理解錯了,卡了好久,網上的答案也看不懂,看清了題目之后覺得不難

兩個要點:

1.用到二分法對刪除的那個數組進行二分

2.判斷刪除字符后的t中是否還含有p,代碼:


for(i=1;i<=l1;i++)
        b[i]=0;
    for(i=1;i<=m;i++)
        b[a[i]]=1;
    for(i=1;i<=l1;i++)
    {
        if(!b[i]) continue;
        if(s1[1]==s2[cnt]) cnt++;
        if(cnt>l2)  return 1;
    }



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