e-olymp
Competitions

Graphs Representation

Loops

The adjacency matrix of an undirected graph is given. Determine whether it contains loops.

Input

The first line contains the number of vertices n (1n100). Then given n lines with n elements in each - the description of adjacency matrix.

Output

Print "YES" if graph contains loops and "NO" otherwise.

Time limit 1 second
Memory limit 128 MiB
Input example #1
3
0 1 1
1 0 1
1 1 0
Output example #1
NO
Input example #2
3
0 1 0
1 1 1
0 1 0
Output example #2
YES