## An Important Letter

Points: 12 (partial)
Time limit: 2.0s
Memory limit: 64M

Author:
Problem type

You have an important letter to deliver to Evan. It must be hand-delivered, but because there are so many others after him, you may not be able to reach him directly. There are $$N$$ students in the school, who may help you deliver your letter, at a certain cost. Person $$a_i$$ will deliver a letter to person $$b_i$$ at a cost of $$c_i$$. There are $$M$$ such options.

You, however, have friends. A friend group is defined as follows: anyone of a friend group is able to deliver a letter directly or indirectly to any other person of the friend group. Formally, the directed edges of a friend group form a cycle. In friend groups, there are no costs of deliver letters.

You would like to find the cheapest cost of delivering your letter to Evan.

#### Constraints

$$2 \leq N \leq 10^4$$

$$0 \leq M \leq 10^5$$

$$1 \leq A, B, a_i, b_i \leq N$$

$$A \neq B$$

$$a_i \neq b_i$$

$$0 \leq c_i \leq 10^4$$

#### Input Specification

The first line of input will contain integers $$N, M, A$$, and $$B,$$ where $$A$$ represents you and $$B$$ represents Evan.

The next $$M$$ lines contain integers $$a_i, b_i, c_i.$$

#### Output Specification

Print one number, the minimum possible cost of delivering your letter to Evan.

If it is not possible for Evan to receive your message, print No Friends.

#### Sample Input 1

7 8 1 7
1 2 1
2 3 2
3 4 2
4 1 5
4 5 2
5 6 1
3 6 9
6 7 5

#### Sample Output 1

8

#### Explanation

$$1, 2, 3,$$ and $$4$$ form a friend group, so you can deliver your message to $$4$$ at no cost, then $$4$$ delivers to $$5,$$ then $$5$$ to $$6,$$ then $$6$$ to Evan.

This gives a total cost of $$2 + 1 + 5 = 8$$

#### Sample Input 2

4 4 1 4
1 2 1
2 3 1
3 2 1
3 4 1

#### Sample Output 2

2