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 Python (3.4.3) (judge verdict: Accepted)

n=int(input())
k=int(input())
def nishinsu(i,n): #iの２進数を文字で返す n桁で
    return str(bin(i)[2:]).zfill(n)
l=[]
for i in range(0,int("1"*n,2)): #n回の操作を行うのに、必要な組み合わせ
    s=1
    for j in nishinsu(i,n): #10001などを左からみていく
        if j=="0":
            s=s*2
        else:
            s=s+k
    l.append(s)
print(min(l))