In a 2D matrix, you are given housing of n people where 1 represents the houses and 0 represents the empty places.

Question: Show the number of houses which have at least two neighbors.

Input specification: First, you will be given an integer: the size of 2D matrix (n). The following n lines contain n integers (one or zero) where 1 ≤ n ≤ 100.

Output specification: Show one integer.