FormulaCheck

Time Limit: 1000 ms Memory Limit: 65536 KiB

Problem Description

The formula for computing the sum of the first n positive whole numbers is based on the idea of finding their average and then multiplying that by the number of numbers.

The average of the numbers between 1 and n is given by

Hence the sum of the number must be

Write a Java application program to check if this formula is correct.

Input

A  positive number

Output

If this formula is correct,please give the output true.

Sample Input

3
9

Sample Output

true
true

Hint

Source

maxj