#3583. Little Artem and Graph
Little Artem and Graph
说明
G. Little Artem and Graph
time limit per test
12 secondsmemory limit per test
256 megabytesinput
standard inputoutput
standard outputLittle Artem is given a graph, constructed as follows: start with some k-clique, then add new vertices one by one, connecting them to k already existing vertices that form a k-clique.
Artem wants to count the number of spanning trees in this graph modulo 109+7.
Input
First line of the input contains two integers n and k (1≤n≤10000, 1≤k≤min(n,5))− the total size of the graph and the size of the initial clique, respectively.
Next n-k lines describe k+1-th, k+2-th, ..., i-th, ..., n-th vertices by listing k distinct vertex indices 1≤aij<i it is connected to. It is guaranteed that those vertices form a k-clique.
Output
Output a single integer− the number of spanning trees in the given graph modulo 109+7.
Examples
Input
3 2
1 2
Output
3
Input
4 3
1 2 3
Output
16