Given a square matrix of binary values find the largest square filled with 1s.

Input:
First line: size of matrix N
Then N lines follow, each contains N numbers.

Output:
Print the length of the size of the largest square filled with ones

Sample input:
4
0 0 1 0
0 0 1 1
1 1 1 1
0 0 1 1

Sample output:
2