Just minimize the max length of a single cable,then output all the edges that shorter then max or equal.
GL

yes but in example test
4 6
1 2 1
1 3 1
1 4 2
2 3 1
3 4 1
2 4 1
max is 1 and you must print
1
5
1 2
1 3
2 3
3 4
2 4
but answer is
1
4
1 2
1 3
2 3
3 4

There are multiple answers satisfy the condition.
Both you wrote are correct.