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 CSharpSample01
{

    
    class Program
    {

        //操作Aと操作Bのうち、より小さい解を選ぶ
        static int Solve(int N, int K)
        {
            int rec = 1;

            for(int i = 0; i < N; i++)
            {
                if (rec * 2 < rec + K) rec *= 2;  //操作A
                else rec += K;  //操作B
            }

            return rec;
        }

        static void Main(string[] args)
        {
            int N = int.Parse(Console.ReadLine());
            int K = int.Parse(Console.ReadLine());

            Console.WriteLine(Solve(N, K));
        }
    }
}