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: Wrong Answer)

using System;

namespace ACpra4
{
    class Program
    {
        static void Main(string[] args)
        {

            int N = int.Parse(Console.ReadLine());
            int K = int.Parse(Console.ReadLine());
            if(N == 1)
            {
                Console.Write(2);   
            }
            if (N == 2)
            {
                if (K ==1)
                {
                    Console.Write(3);
                }
                else if (2<= K && K<= 10)
                {
                    Console.WriteLine(4);
                }
            }
            if(N == 3)
            {
                if(K == 2)
                {
                    Console.Write(6);
                }else if(K == 3)
                {
                    Console.Write(8);
                }
                else if(K == 1)
                {
                    Console.Write(4);
                }else if(K >=4)
                {
                    Console.Write(8);
                }
            }
            if (N >= 4)
            {
                if(K == 1)
                {
                    Console.Write(N * K);
                }else if(K == 2 || K == 3)
                {
                    Console.Write(4 + (N-2) * K);
                }else if(K>=4&&K < 8)
                {
                    Console.Write(8 + (N - 3) * K);
                }
             
                
                else if(K >= 8 && K < 11)
                { 
                    Console.Write(16 + ((N - 4) * K));
                }
            }
        }
    }
}