After acquiring enough funding and finally finishing the development for her product, Mrs. Evans wants to release it to the local market. However, the Canadian Competition Act prevents her from choosing the cheapest way to connect her stores.
In order to spend the least amount of money and abide by the Canadian Competition Act, she must find the second cheapest way to connect her stores.
Mrs. Evans hopes to open
stores and there are
possible connections between her stores. The
connection connects station
to station
with a cost of
. She can only choose
connections.
If it is impossible for her to do this, output -1
.
N.B. The time limit is rather strict for certain slow languages like Python and Java. C++ is recommended for this question.
Partial Marks
For 25% of the marks, you may assume that ,
.
For 50% of the marks, you may assume that ,
.
Input Specification
The first line will contain , and
. The
of the next
lines will contain
,
, and
, where
.
Output Specification
A single line containing the second cheapest way to connect her stores.
Sample Input 1
3 3
1 2 1
2 3 2
3 1 3
Sample Output 1
4
Explanation for Sample Output 1
Mrs. Evans chooses the following connections for a total cost of :
with cost
with cost
Sample Input 2
5 10
2 3 5
1 5 5
1 2 3
1 3 2
5 3 2
4 3 3
4 5 9
4 2 10
5 2 4
4 1 9
Sample Output 2
11
Explanation for Sample Output 2
Mrs. Evans chooses the following connections for a total cost of :
with cost
with cost
with cost
with cost
Comments
When you say if it is possible, I think you mean the opposite.
Relevant: In re Sample Input 2, CAN IT BE?