Dijkstra

Description:

Input:

The first line contains two integers $$$n, m$$$ ($$$1 \leq n, m \leq 2 \cdot 10^5$$$) — the number of vertices and the number of edges.

Each of the next $$$m$$$ lines contain description of an edge $$$a_i~b_i~cost_i$$$ ($$$1 \leq a_i, b_i \leq n$$$, $$$1 \leq cost_i \leq 10^9$$$).

Loops and multiple edges? Hmm, why not?

Output:

Print one integer — the answer to the problem. If there is no path, print $$$-1$$$ instead.

Sample Input:

3 3
1 2 5
2 3 1
1 3 7

Sample Output:

6