Problem Statement

Mitaru City has $\ N\ $ towns and $\ M\ $ roads.
The $i\ $-th town $\ (1\leq i\leq N)\ $ has $\ p_i\ $ residents.
The $\ i\ $-th road $\ (1\leq i\leq M)\ $ bidirectionally connects the $\ a_i\ $-th town and the $\ b_i\ $-th town.
It is guaranteed that for any pair of $\ 2\ $ towns, at most $\ 1\ $ road directly connects them.

You have variables $\ X,Y\ $ and are initially in town $\ S\ $. In the initial state, $\ X=p_S,Y=0\ $ holds.

From now on, you repeat the following action.

Choose $\ 1\ $ town directly connected by a road to the town you are currently in, and go to that town. Letting that town be the $\ i\ $-th town, if $\ X>p_i\ $, set $\ X=p_i\ $ and add $\ 1\ $ to $\ Y\ $.

When you act appropriately so that $\ Y\ $ at the time of ending the operation is maximized and then end the operation, find the value of $\ Y\ $ at the time of ending the operation.

Input

$N\ \ M\ \ S\ \ T$
$p_1\ \ p_2\ \ \cdots p_N$
$a_1\ \ b_1$
$a_2\ \ b_2$
$\vdots$
$a_M\ \ b_M$

• $2 \leq N \leq 10^5$
• $1 \leq M \leq 10^5$
• $1 \leq S,T \leq N$
• $S \neq T$
• $1 \leq p_i \leq 10^9(1 \leq i \leq N)$
• $1 \leq a_i < b_i \leq N(1 \leq i \leq M)$
• $(a_i,b_i) \neq (a_j,b_j) (i \neq j)$
• All inputs are integers.
• It is guaranteed that from $S\ $ you can reach $\ T\ $ by traversing some roads.

Output

When you act appropriately so that $\ Y\ $ at the time of ending the operation is maximized and then end the operation, output the value of $\ Y\ $ at the time of ending the operation, followed by a newline.

Sample

4 4 3 4
8 3 5 2
1 4
2 3
1 2
3 4

2

2 1 1 2
1 2021
1 2

0

7 8 3 7
12 23 34 45 56 67 78
1 4
2 3
4 7
5 6
2 7
6 7
1 5
2 5

2