Codeforces Round 546 (Div. 2)
D
Nastya Is Buying Lunch
Codeforces
1800
原题
← CE →
翻译中…

At the big break Nastya came to the school dining room. There are $n$ pupils in the school, numbered from $1$ to $n$. Unfortunately, Nastya came pretty late, so that all pupils had already stood in the queue, i.e. Nastya took the last place in the queue. Of course, it's a little bit sad for Nastya, but she is not going to despond because some pupils in the queue can agree to change places with some other pupils.

翻译中…

Formally, there are some pairs $u$, $v$ such that if the pupil with number $u$ stands directly in front of the pupil with number $v$, Nastya can ask them and they will change places.

翻译中…

Nastya asks you to find the maximal number of places in queue she can move forward.

翻译中…

Input

翻译中…

The first line contains two integers $n$ and $m$ ($1 \leq n \leq 3 \cdot 10^{5}$, $0 \leq m \leq 5 \cdot 10^{5}$) — the number of pupils in the queue and number of pairs of pupils such that the first one agrees to change places with the second one if the first is directly in front of the second.

翻译中…

The second line contains $n$ integers $p_1$, $p_2$, ..., $p_n$ — the initial arrangement of pupils in the queue, from the queue start to its end ($1 \leq p_i \leq n$, $p$ is a permutation of integers from $1$ to $n$). In other words, $p_i$ is the number of the pupil who stands on the $i$-th position in the queue.

翻译中…

The $i$-th of the following $m$ lines contains two integers $u_i$, $v_i$ ($1 \leq u_i, v_i \leq n, u_i \neq v_i$), denoting that the pupil with number $u_i$ agrees to change places with the pupil with number $v_i$ if $u_i$ is directly in front of $v_i$. It is guaranteed that if $i \neq j$, than $v_i \neq v_j$ or $u_i \neq u_j$. Note that it is possible that in some pairs both pupils agree to change places with each other.

翻译中…

Nastya is the last person in the queue, i.e. the pupil with number $p_n$.

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Output

翻译中…

Print a single integer — the number of places in queue she can move forward.

翻译中…

Note

翻译中…

In the first example Nastya can just change places with the first pupil in the queue.

翻译中…

Optimal sequence of changes in the second example is

翻译中…
  • change places for pupils with numbers $1$ and $3$.
  • change places for pupils with numbers $3$ and $2$.
  • change places for pupils with numbers $1$ and $2$.
翻译中…

The queue looks like $[3, 1, 2]$, then $[1, 3, 2]$, then $[1, 2, 3]$, and finally $[2, 1, 3]$ after these operations.

翻译中…

样例

Input #1
2 1
1 2
1 2
Output #1
1
InputCopy OutputCopy
Input #2
3 3
3 1 2
1 2
3 1
3 2
Output #2
2
InputCopy OutputCopy
Input #3
5 2
3 1 5 4 2
5 2
5 4
Output #3
1
InputCopy OutputCopy
题目信息
题号
1136D
时间限制
2 s
内存限制
256 MB
标签
贪心

题面与样例版权归 Codeforces 及出题人所有;中文翻译由 AI 生成(CI 管线),如有出入请以原文为准。