using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine(Solution.CountVowelPermutation(5));

    }

}

​

public class Solution {

    public static int CountVowelPermutation(int n) {

        //a=0, e=1, i=2, o=3, u=4        

        //a = e,i,u || e = a,i || i = e,o || o = i || u = i,o

        //0=>1,2,4 || 1=>0,2 || 2=>1,0 || 3=>2 || 4=>2,3

        long vowA = 1;

        long vowE = 1;

        long vowI = 1;

        long vowO = 1;

        long vowU = 1;

        long MOD = Math.Pow(10,9) + 7;

        Console.WriteLine("Mod is {0}", MOD);

        for(int i=1;i<n;i++){

            var vowAnew = (vowE + vowI + vowU) % MOD;

            var vowEnew = (vowA + vowI) % MOD;

            var vowInew = (vowE + vowO) % MOD;

            var vowOnew = (vowI) % MOD;

            var vowUnew = (vowO + vowI) % MOD;

            vowA = vowAnew;

            vowE = vowEnew;

            vowI = vowInew;

            vowO = vowOnew;

            vowU = vowUnew;

        }

        var sum = (vowA + vowE + vowI + vowO + vowU);

        sum = sum%MOD;

        return (int)sum;

    }

}