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 System.Text;
using System.Threading.Tasks;

namespace AtCoder.Abc
{
    class Abc_049_C
    {
        // https://atcoder.jp/contests/abc049/tasks/arc065_a
        public static void Main(string[] args)
        {
            var sw = new System.IO.StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false };
            Console.SetOut(sw);

            string[] divide = new string[4]{ "dream", "dreamer", "erase", "eraser" };

            for (int k = 0; k < 4; ++k) divide[k] = new string(divide[k].Reverse().ToArray());
            // 文字列の入力
            string s = Console.ReadLine();
            s = new string(s.Reverse().ToArray());
            string result = "NO";
            bool can = true;
            for (int i = 0; i < s.Length; i++)
            {
                bool can2 = false;
                for (int j = 0; j < 4; j++)
                {
                    string d = divide[j];
                    if ((s.Length > d.Length && s.Substring(i, d.Length) == d) || s == d)
                    {
                        can2 = true;
                        i += d.Length;
                    }
                }
                if (!can2)
                {
                    can = false;
                    break;
                }
            }

            if (can) result = "YES";
            Console.WriteLine(result);

            Console.Out.Flush();
        }
    }
}