# Marble exchanges

0.65 Edgar has a collection of red, blue and yellow marbles. As many
times as he wishes, he can only make one operation: exchanging two
marbles of different colours (one of each colour) for one of the
remaining colour. Given $(R, B, Y)$ (the number of marbles of each
colour), can you determine whether Edgar will be capable of keeping just
one of the marbles?

For instance, from $(1, 1, 2)$ he can move to $(2, 0, 1)$, from there to
$(1, 1, 0)$, and from there to $(0, 0, 1)$. By contrast, it is not
difficult to see that from $(1, 1, 3)$ he cannot reach any of
$(1, 0, 0)$, $(0, 1, 0)$ or $(0, 0, 1)$.

0.33

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![image](marbles.eps){width="5.3cm"}
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## Input

Input consists of several cases, each one with three integers $R$, $B$
and $Y$, all of them between 0 and $10^9$. Assume $R + B + Y > 0$.

## Output

For every case, print "`YES`" if Edgar can achieve a situation where
$R' + B' + Y' = 1$, and print "`NO`" otherwise. Obviously, none of the
three variables can go below zero at any moment.

## Problem information

Author: Jordi Rodriguez

Generation: 2026-01-25T10:21:58.958Z

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