A sample Hamilton path

Give you a Graph,you have to start at the city with ID zero.

The first line is n(1<=n<=21) m(0<=m<=3)
The next n line show you the graph, each line has n integers.
The jth integers means the length to city j.if the number is -1 means there is no way. If i==j the number must be -1.You can assume that the length will not larger than 10000
Next m lines,each line has two integers a,b (0<=a,b<n) means the path must visit city a first.
The input end with EOF.

For each test case,output the shorest length of the hamilton path.
If you could not find a path, output -1

3 0
-1 2 4
-1 -1 2
1 3 -1
4 3
-1 2 -1 1
2 -1 2 1
4 3 -1 1
3 2 3 -1
1 3
0 1
2 3

4
5

I think that all of you know that a!=b and b!=0 =。=

2010 ACM-ICPC Multi-University Training Contest（11）——Host by BUPT