#include using namespace std; typedef long long ll; #define REP(i,n) for(int i=0; i #define VLL vector #define VVI vector> #define VVLL vector> #define VC vector #define VS vector #define VVC vector> #define VB vector #define VVB vector> #define fore(i,a) for(auto &i:a) typedef pair P; template bool chmax(T &a, T b) { if (a < b) { a = b; return true; } return false; } template bool chmin(T &a, T b) { if (a > b) { a = b; return true; } return false; } const int INF = 1 << 30; const ll INFL = 1LL << 60; const ll mod = 998244353; int main() { int n, k; cin >> n >> k; n -= k; if (n < 0) { cout << 0 << endl; return 0; } cout << (int)pow(2, n) << endl; }