Boss, if $N≤30\, 000$, you should try to optimise the $N^2$ solution. (Friedrich Nietzsche)
Let $G$ be a undirected connected graph with $N$ nodes and $M$ edges. Label each of the $M$ edges with a distinct integer from $1$ to $M$. For each node with degree greater than $1$, the greatest common divisor of its incident edges' labels should be $1$.
The first line contains two integers $N$ and $M$.
The next $M$ lines contain two integers $u$ and $v$, representing two nodes that share an edge.
Print $M$ lines, each containing three integers $u$, $v$ and $c$ corresponding to an edge with label $c$ between $u$ and $v$.