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Description

There is a square with the coordinates of its four corners ($x$, $y$) being ($1$, $-1$), ($1$, $1$), ($-1$, $-1$), and ($-1$, $1$), where $x$ is the horizontal axis and $y$ is the vertical axis.
Write a program to determine if a given point is inside this square (including the square's boundary).

Input Format

Input a single line containing two integers $x$ and $y$, separated by a space, representing the coordinates ($x$, $y$) ($-10 \le x, y \le 10$).

Output Format

Output a single line. If the point is inside the square, output "yes"; otherwise, output "no".

Sample

1 1

yes