Problems
Number of hanging vertices 1
Number of hanging vertices 1
Given a simple undirected unweighted graph. Count the number of hanging vertices in it. The vertex is hanging, if its degree is 1.
Input data
The first line contains number n~(1 \le n \le 1000). The next n lines contain the adjacency matrix.
Output data
Print the number of hanging vertices in a graph.
Examples
Input example #1
2 0 1 1 0
Output example #1
2
Input example #2
3 0 1 1 1 0 1 1 1 0
Output example #2
0