using System;

using System.Collections.Generic;

using System.Linq;

using System.Numerics;

​

public class Program

{

    private static int ModPow(IEnumerable<int> values)

    {

        return values.Reverse().Aggregate(0, (exponent, value) => Convert.ToInt32(Math.Pow(value, exponent) % 10));

    }

​

    private static int ModBigPow(IEnumerable<int> values)

    {

        return (int)values.Reverse().Select(val => new BigInteger(val)).Aggregate(BigInteger.Zero, (exponent, value) => BigInteger.ModPow(value, exponent, 10));

    }

}