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)

#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0;i<n;i++)
#define mfill(x,y) memset(x,y,sizeof(x))
#define all(v) v.begin(), v.end()
#define in(x,y,h,w) if(0<=x&&x<h&&0<=y&&y<w)
#define y0 y12345
#define y1 y54321

#ifdef LOCAL
#define debug(...) fprintf(stderr,__VA_ARGS__)
#else
#define debug(...) 42
#endif

using ul = unsigned long;
using ll = long long;
using P = pair<int, int>;
using vint = vector<int>;using vvint = vector<vector<int>>;
using vll = vector<ll>;using vvll = vector<vector<ll>>;
template<class T>bool chmax(T &a, const T &b){if(a<b){a=b;return 1;}return 0;}
template<class T>bool chmin(T &a, const T &b){if(a>b){a=b;return 1;}return 0;}
template <class T>void initvv(vector<vector<T> > &v, int a, int b, const T &t = T()){
	v.assign(a, vector<T>(b, t));
}
template <class T>T gcd(T &a, T &b){if(a<b){swap(a,b);} T r = a%b; while(r!=0){a=b;b=r;r=a%b;} return b;}

vint dx = {-1, 0, 1, 0}, dy = {0, -1, 0, 1};
vint dx8 = {-1, -1, -1, 0, 1, 1, 1, 0}, dy8 = {-1, 0, 1, 1, 1, 0, -1, -1};

int main() {
	cin.tie(0);
   	ios::sync_with_stdio(false);
	debug("debug test\n");
   	int n,m,k;cin>>n>>k;
	int s = 1;
	rep(i, n){
		if(s < k){
			s*=2;
		}else{
			s+=k;
		}
	}
	cout << s << endl;
	return 0;
}