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 JavaScript (node.js v5.12) (judge verdict: Accepted)

const input = require("fs").readFileSync("/dev/stdin", "utf8").split("\n");

const N = input[0].split(' ').map(item => parseInt(item))[0]
const K = input[1].split(' ').map(item => parseInt(item))[0]

const greedy = (value, n, k) => {
    if (n == 0) {
        return value
    }
    if (n > 0) {
        a = value * 2
        b = value + k
        a < b ? value = a : value = b
        return greedy(value, n - 1, k)
    }
}

console.log(greedy(1, N, K))