#include <bits/stdc++.h>

int dfs(bool checked[32], int i, int n, int prev, int rem) {
  if( i == n and rem == 0 ) {
    return 1;
  }
  int res = 0;
  if( rem == 1 ) {
    for(int j = 1; j <= n; ++j) {
      if( checked[j] ) continue;
      checked[j] = true;
      int rem2 = (j < prev ? 0 : 1);
      res += dfs(checked, i + 1, n, j, rem2);
      checked[j] = false;
    }
  }
  if( rem == 0 ) {
    bool end = false;
    for(int j = 1; j < prev; ++j) {
      if( not checked[j] ) end = true;
    }
    if( end ) return 0;
    for(int j = prev + 1; j <= n; ++j) {
      if( checked[j] ) continue;
      checked[j] = true;
      res += dfs(checked, i + 1, n, j, 0);
      checked[j] = false;
    }
  }
  return res;
}

int solve(int n, int k) {
  bool checked[32] = {};
  checked[k] = true;
  return dfs(checked, 1, n, k, 1);
}

int main() {
  int n, k;
  scanf("%d %d", &n, &k);

  printf("%d\n", solve(n, k));

  return 0;
}