Problem:
Score : 100 points

Problem Statement

Given a lowercase English letter c, determine whether it is a vowel. Here, there are five vowels in the English alphabet: a, e, i, o and u.

Constraints

c is a lowercase English letter.

Input

The input is given from Standard Input in the following format:

c

Output

If c is a vowel, print vowel. Otherwise, print consonant.

Sample Input 1

a

Sample Output 1

vowel

Since a is a vowel, print vowel.

Sample Input 2

z

Sample Output 2

consonant

Sample Input 3

s

Sample Output 3

consonant

Solution in C# (Mono 4.6.2.0) (judge verdict: Wrong Answer)

using System;
using System.Collections.Generic;
using System.Linq;
using static System.Console;
using static System.Math;
using static ConsoleApplication.Utils;

namespace ConsoleApplication
{
    public class Program
    {
        public static void Main(string[] args)
        {
            var c = ReadLine().First();
            switch(c)
            {
                case 'a':
                case 'e':
                case 'i':
                case 'o':
                    WriteLine("vowel");
                    break;
                default:
                    WriteLine("consonant");
                    break;
            }
        }
    }

    public static class Utils
    {
        #region Extensions for IO

        public static int ReadInt()
            => ReadLine().ToInt();

        public static IEnumerable<int> ReadInts()
            => ReadStrings().Select(int.Parse);

        public static IEnumerable<int> ReadInts(int count)
            => ReadLines(count).Select(int.Parse);

        public static long ReadLong()
            => ReadLine().ToLong();

        public static IEnumerable<long> ReadLongs()
            => ReadStrings().Select(long.Parse);

        public static ulong ReadUlong()
            => ReadLine().ToUlong();

        public static IEnumerable<ulong> ReadUlongs()
            => ReadStrings().Select(ulong.Parse);


        public static IEnumerable<string> ReadStrings()
            => ReadLine().Split(' ');

        public static IEnumerable<string> ReadLines(int n)
        {
            foreach (var i in Enumerable.Range(0, n))
            {
                yield return ReadLine();
            }
        }

        #endregion

        #region Extensions of int

        public static bool IsOdd(this int n)
            => !n.IsEven();

        public static bool IsEven(this int n)
            => n % 2 == 0;

        public static bool CanDivideWith(this int n, int divisor)
            => n % divisor == 0;

        #endregion

        #region Extensions of string

        public static int ToInt(this string str)
            => int.Parse(str);

        public static long ToLong(this string str)
            => long.Parse(str);

        public static ulong ToUlong(this string str)
            => ulong.Parse(str);

        public static double ToDouble(this string str)
            => double.Parse(str);

        public static bool IsNullOrEmpty(this string str)
            => string.IsNullOrEmpty(str);

        #endregion

        public static TSource Min<TSource, TKey>(this IEnumerable<TSource> source, Func<TSource, TKey> keySelector)
            where TKey : IComparable
            => source.OrderBy(keySelector).First();

        public static TSource Max<TSource, TKey>(this IEnumerable<TSource> source, Func<TSource, TKey> keySelector)
            where TKey : IComparable
            => source.OrderByDescending(keySelector).First();

        public static void ForEach<T>(this IEnumerable<T> source, Action<T> action)
        {
            foreach (var item in source)
            {
                action(item);
            }
        }

        public static IEnumerable<T> Peek<T>(this IEnumerable<T> source, Action<T> action)
        {
            foreach (var item in source)
            {
                action(item);
            }
            return source;
        }
    }
}