Addition and Multiplication

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.

Examples

Input

4 3

Output

10

Input

10 10

Output

76

inputFormat

input values are integers.

Input

Input is given from Standard Input in the following format:

N K

outputFormat

Output

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

Examples

Input

4 3

Output

10

Input

10 10

Output

76

样例

10
10

76