Problem:
Score : 200 points

Problem Statement

Square1001 has seen an electric bulletin board displaying the integer 1.
He can perform the following operations A and B to change this value:

Operation A: The displayed value is doubled.

Operation B: The displayed value increases by K.

Square1001 needs to perform these operations N times in total.
Find the minimum possible value displayed in the board after N operations.

Constraints

1 \leq N, K \leq 10

All input values are integers.

Input

Input is given from Standard Input in the following format:

N
K

Output

Print the minimum possible value displayed in the board after N operations.

Sample Input 1

4
3

Sample Output 1

10

The value will be minimized when the operations are performed in the following order: A, A, B, B.

In this case, the value will change as follows: 1 → 2 → 4 → 7 → 10.

Sample Input 2

10
10

Sample Output 2

76

The value will be minimized when the operations are performed in the following order: A, A, A, A, B, B, B, B, B, B.

In this case, the value will change as follows: 1 → 2 → 4 → 8 → 16 → 26 → 36 → 46 → 56 → 66 → 76.

By the way, this contest is AtCoder Beginner Contest 076.

Solution in C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
using System.Collections.Generic;
using System.Linq;

namespace ConsoleApp1
{
    public static class MyExtensions
    {
        public static string Slice(this string str, int start = 0, int stop = 0)
        {
            if (start > str.Length || stop > str.Length || start < 0 || stop < 0)
                return "";

            if (stop == 0) stop = str.Length;
            return str.Substring(start, stop - start);
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            B();
        }

        static void B()
        {
            var N = ReadInt();
            var K = ReadInt();
            var ans = 1;
            for (int i = 0; i < N; i++)
            {
                ans = Math.Min(ans * 2, ans + K);
            }
            Console.WriteLine(ans);
        }

        public static IEnumerable<int> Range(int start, int stop)
        {
            if (start < 0 || stop < 0)
                throw new Exception("0未満");

            if (start > stop || (start == 0 && stop == 0))
                return new List<int>();

            return Enumerable.Range(start, stop - start);
        }

        public static bool IsDigit(string str)
        {
            var i = 0;
            return int.TryParse(str, out i);
        }

        public static int DigitsSum(long num)
        {
            return num.ToString().Select(x => x.ToString()).Sum(int.Parse);
        }

        public static int[] ToIntArray(string str)
        {
            return str.Select(x => x.ToString()).Select(int.Parse).ToArray();
        }

        public static string Read()
        {
            return Console.ReadLine();
        }

        public static IList<int> ReadIntInputs()
        {
            return Read().Split(' ').Select(int.Parse).ToList();
        }

        public static int ReadInt()
        {
            return int.Parse(Read());
        }

        public static IList<string> ReadInputs()
        {
            return Read().Split(' ').ToList();
        }
    }
}