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CSES Problem Set

Edge Directions


Task | Statistics


CSES - Edge DirectionsCSES - Edge Directions

Time limit:1.00 s Memory limit:512 MB

Given an undirected graph, your task is to choose a direction for each edge so that the resulting directed graph is acyclic.

Input

The first input line has two integers $n$ and $m$: the number of nodes and edges. The nodes are numbered $1,2,\dots,n$.

After this, there are $m$ lines describing the edges. Each line has two distinct integers $a$ and $b$: there is an edge between nodes $a$ and $b$.

Output

Print $m$ lines describing the directions of the edges. Each line has two integers $a$ and $b$: there is an edge from node $a$ to node $b$. You can print any valid solution.

Constraints
Example

Input:
3 3
1 2
2 3
3 1


Output:
1 2
3 2
3 1