codeforces#P1663E. Are You Safe?

Are You Safe?

Description

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.

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

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

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 $n$.

Samples

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