Problems

# Square

Four positive integers a, b, c, d are given. Find the square of any given number if there exists a square with side lengths a, b, c, d and No otherwise.

#### Input

Four positive integers a, b, c, d, each no more than 109.

#### Output

If the square exists, print the square of any input number. Otherwise print No.

Time limit 1 second
Memory limit 128 MiB
Input example #1
7 7 7 7

Output example #1
49

Input example #2
9 6 9 6

Output example #2
No

Author Matviychuk Sergiy Volodymyrovych
Source "ABC programming"