Competitions

# Graph representation

# Count number of edges

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 a 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.

Input example #1

3 0 1 1 1 0 1 0 1 1

Output example #1

6