E. Are You Safe?
time limit per test
1 second
memory limit per test
256 megabytes
input
standard input
output
standard output

Seven boys and seven girls from Athens were brought before King Minos. The evil king laughed and said "I hope you enjoy your stay in Crete".

With a loud clang, the doors behind them shut, and darkness reigned. The terrified children huddled together. In the distance they heard a bellowing, unholy roar.

Bravely, they advanced forward, to their doom.

Input

$$$n$$$ ($$$1 \le n \le 100$$$) — the dimensions of the labyrinth.

Each of the next $$$n$$$ lines contains a string of lowercase English letters of length $$$n$$$.

Example
Input
10
atzxcodera
mzhappyayc
mineodteri
trxesonaac
mtollexcxc
hjikeoutlc
eascripsni
rgvymnjcxm
onzazwswwg
geothermal
Output
YES