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 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <stdio.h>

int main()
{
	int N, K, i, total1 = 1, total2 = 1, total3 = 1;
	scanf("%d %d", &N, &K);
	for (i = 0; i < N ; i++) {
		if (i < N / 2)
			total1 *= 2;
		else
			total1 += K;
		
		if (i < N / 2 - 1)
			total2 *= 2;
		else
			total2 += K;
		
		if (i < N / 2 + 1)
			total3 *= 2;
		else
			total3 += K;
	}
	if (total1 < total2 && total1 < total3)
		printf("%d\n", total1);
	else if (total2 < total3)
		printf("%d\n", total2);
	else
		printf("%d\n", total3);
	return 0;
}