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Thailand National Olympiad
2010 Thailand Mathematical Olympiad
8
8
Part of
2010 Thailand Mathematical Olympiad
Problems
(1)
modulo 2553 distance d(m, n) <= 36 , |S| >= 70
Source: 2010 Thailand Mathematical Olympiad day 1 p8
3/12/2021
Define the modulo
2553
2553
2553
distance
d
(
x
,
y
)
d(x, y)
d
(
x
,
y
)
between two integers
x
,
y
x, y
x
,
y
to be the smallest nonnegative integer
d
d
d
equivalent to either
x
−
y
x - y
x
−
y
or
y
−
x
y - x
y
−
x
modulo
2553
2553
2553
. Show that, given a set S of integers such that
∣
S
∣
≥
70
|S| \ge 70
∣
S
∣
≥
70
, there must be
m
,
n
∈
S
m, n \in S
m
,
n
∈
S
with
d
(
m
,
n
)
≤
36
d(m, n) \le 36
d
(
m
,
n
)
≤
36
.
number theory
distance