Parity of the number of divisors P24818


Statement
 

pdf   zip

html

Write a program that reads a sequence of natural numbers and, for each one, tells if its number of divisors is even or odd.

For instance, 18 has 6 divisors (1, 2, 3, 6, 9 and 18), and 100 has 9 (1, 2, 4, 5, 10, 20, 25, 50 and 100).

Input

Input consists of a sequence of strictly positive natural numbers.

Output

Print each given number followed by “even” or “odd”, as required.

Observation

The trivial algorithm to solve this exercise is too slow. The fastest algorithm uses the square root. Try to find an intermediate solution.

Public test cases
  • Input

    18
    100
    

    Output

    18: even
    100: odd
    
  • Information
    Author
    Salvador Roura
    Language
    English
    Translator
    Carlos Molina
    Original language
    Catalan
    Other languages
    Catalan
    Official solutions
    C++
    User solutions
    C++