Farmer John is attempting to take a photograph of his herd of cows. From past
experience, he knows this particular endeavor never usually ends well.

This time, Farmer John has purchased an expensive drone in order to take an
aerial photo. To make the photo look as good as possible, he wants his cows all
to be facing the same direction when the photo is taken. The cows are currently arranged
in an \(N \times N\) grid (\(2 \leq N \leq 1000\)) inside a fenced-in square
pasture, for example:

RLR
RRL
LLR

Here, an 'R' means a cow facing right, and an 'L' means a cow facing left. Since
the cows are packed together, Farmer John cannot walk up to an individual cow to
make it turn around. All he can do is shout at any row or column of cows to
turn around, causing L's to change to R's and R's to L's within the row or
column in question. Farmer John can yell at as many rows or columns as he
wants, even at the same row or column more than once.

As expected, Farmer John observes that he is unable to make his cows all face
one common direction. The best he can do is get all but one of the cows to face
the same direction. Please determine the identity of such a cow.

Problem credits: Brian Dean

Problem credits: Brian Dean

The first line contains \(N\). The next \(N\) lines describe rows \(1 \ldots N\) in
the grid of cows, each containing a string of length \(N\).

Print the row and column index of a cow such that if that cow were flipped,
Farmer John could make all his cows face the same direction. If no such cow
exists, print -1. If multiple such cows exist, print the one with the smallest
row index, or if multiple such cows have the same smallest row index, print the
one with the smallest column index.

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출처 올림피아드 > USACO > 2018-2019 > US Open > Silver