#define _USE_MATH_DEFINES #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; typedef long double ld; typedef long long ll; typedef unsigned long long ull; typedef pair i_i; typedef pair ll_i; typedef pair i_ll; typedef pair d_i; typedef pair ll_ll; typedef pair d_d; struct edge { int u, v; ll w; }; ll MOD = 10007; ll _MOD = 1000000009; double EPS = 1e-10; int main() { int N, K; cin >> N >> K; cout << ((1<<(N - K)) - (K == 1) * (1<<(N - 1))) << endl; }