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++14 (GCC 5.4.1) (judge verdict: Accepted)

/*  
    Talkin' to myself and feelin' old
    Sometimes I'd like to quit, nothin' ever seems to fit
    Hangin' around, nothin' to do but frown
    Rainy days and Mondays always get me down
    _________________________
    _________________________
    912 Hours of Solitude
    Quarantine_Day : 38
*/

#include<bits/stdc++.h>

using namespace std;

typedef long long int       ll;
typedef vector<int>         vi;
typedef vector<ll>          vl;
typedef pair<int, int>      pii;
typedef pair<ll, ll>		pll;

#define pb(n)           push_back(n)
#define GSORT(v)        sort(v.begin(), v.end(), greater<int>())
#define SORT(v)         sort(v.begin(), v.end());
#define REV(v)          reverse(v.begin(), v.end());
#define db(a)           cout<<#a<<" = "<<a<<endl;
#define FIN             freopen("in.txt","r",stdin);
#define FOUT            freopen("out.txt","w",stdout);
#define REP(i,n)        for(int i = (int)(0); i < (int)(n); i++)
#define FOR(i, a, b)    for(int i = (int)a; i <= (int)b; i++)    

#define MAX 50005

int n, k;
int go(int i, int sum){
    if(i > n) return sum;

    int a = go(i + 1, sum * 2);
    int b = go(i + 1, sum + k);

    return min(a, b);
}
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);

    cin>>n>>k;
    cout<<go(1, 1)<<"\n";
    return 0;
}