#D6257. Traveling Salesman Problem
Traveling Salesman Problem
Traveling Salesman Problem
For a given weighted directed graph G(V, E), find the distance of the shortest route that meets the following criteria:
- It is a closed cycle where it ends at the same point it starts.
- It visits each vertex exactly once.
Constraints
- 2 ≤ |V| ≤ 15
- 0 ≤ di ≤ 1,000
- There are no multiedge
Input
|V| |E| s0 t0 d0 s1 t1 d1 : s|E|-1 t|E|-1 d|E|-1
|V| is the number of vertices and |E| is the number of edges in the graph. The graph vertices are named with the numbers 0, 1,..., |V|-1 respectively.
si and ti represent source and target vertices of i-th edge (directed) and di represents the distance between si and ti (the i-th edge).
Output
Print the shortest distance in a line. If there is no solution, print -1.
Examples
Input
4 6 0 1 2 1 2 3 1 3 9 2 0 1 2 3 6 3 2 4
Output
16
Input
3 3 0 1 1 1 2 1 0 2 1
Output
-1
inputFormat
Input
|V| |E| s0 t0 d0 s1 t1 d1 : s|E|-1 t|E|-1 d|E|-1
|V| is the number of vertices and |E| is the number of edges in the graph. The graph vertices are named with the numbers 0, 1,..., |V|-1 respectively.
si and ti represent source and target vertices of i-th edge (directed) and di represents the distance between si and ti (the i-th edge).
outputFormat
Output
Print the shortest distance in a line. If there is no solution, print -1.
Examples
Input
4 6 0 1 2 1 2 3 1 3 9 2 0 1 2 3 6 3 2 4
Output
16
Input
3 3 0 1 1 1 2 1 0 2 1
Output
-1
样例
3 3
0 1 1
1 2 1
0 2 1
-1