题目描述
One day Masha was walking in the park and found a graph under a tree... Surprised? Did you think that this problem would have some logical and reasoned story? No way! So, the problem...
Masha has an oriented graph which $i$-th vertex contains some positive integer $a_i$. Initially Masha can put a coin at some vertex. In one operation she can move a coin placed in some vertex $u$ to any other vertex $v$ such that there is an oriented edge $u \to v$ in the graph. Each time when the coin is placed in some vertex $i$, Masha write down an integer $a_i$ in her notebook (in particular, when Masha initially puts a coin at some vertex, she writes an integer written at this vertex in her notebook). Masha wants to make exactly $k - 1$ operations in such way that the maximum number written in her notebook is as small as possible.
Input
The first line contains three integers $n$, $m$ and $k$ ($1 \le n \le 2 \cdot 10^5$, $0 \le m \le 2 \cdot 10^5$, $1 \le k \le 10^{18}$) — the number of vertices and edges in the graph, and the number of operation that Masha should make.
The second line contains $n$ integers $a_i$ ($1 \le a_i \le 10^9$) — the numbers written in graph vertices.
Each of the following $m$ lines contains two integers $u$ and $v$ ($1 \le u \ne v \le n$) — it means that there is an edge $u \to v$ in the graph.
It's guaranteed that graph doesn't contain loops and multi-edges.
Output
Print one integer — the minimum value of the maximum number that Masha wrote in her notebook during optimal coin movements.
If Masha won't be able to perform $k - 1$ operations, print $-1$.
输入格式
见题面 Input 部分
输出格式
见题面 Output 部分
样例输入
样例输出
提示
Graph described in the first and the second examples is illustrated below.
In the first example Masha can initially put a coin at vertex $1$. After that she can perform three operations: $1 \to 3$, $3 \to 4$ and $4 \to 5$. Integers $1, 2, 3$ and $4$ will be written in the notepad.
In the second example Masha can initially put a coin at vertex $2$. After that she can perform $99$ operations: $2 \to 5$, $5 \to 6$, $6 \to 2$, $2 \to 5$, and so on. Integers $10, 4, 5, 10, 4, 5, \ldots, 10, 4, 5, 10$ will be written in the notepad.
In the third example Masha won't be able to perform $4$ operations.