# Count the number of edges

Execution time limit is 1 second

Runtime memory usage limit is 128 megabytes

The directed graph is given with an adjacency matrix. Find the number of edges in a graph.

## Input

The first line contains the number of vertices in the graph $n(1≤n≤100)$. Then given $n$ lines with $n$ numbers $0$ or $1$ — the adjacency matrix of the graph.

## Output

Print the number of edges in a graph.

## Examples

Input #1

Answer #1

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