From adjacency matrix to the list of edges#2471

From adjacency matrix to the list of edges

1 second
128 megabytes
Very easy

A simple undirected graph is given by adjacency matrix. Print its representation as a list of edges.

Input

The first line contains the number of vertices n~(1 \le n \le 100) in the graph. The next lines contain the adjacency matrix of the graph.

Output

Print the list of edges of the graph, ordered by the first vertex in each pair.

Examples

Example 1

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