Competitions

# Graph 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** (**1** ≤ **n** ≤ **100**). Then given **n** lines with **n** elements in each - the description of adjacency matrix.

#### Output

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

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