#include <bits/stdc++.h>
using namespace std;
const int M = 1000000007;
void add(int &a, int b) {
  a += b;
  if (a >= M) a -= M;
}
int dp[55][55][2];
int c[55][55];
int inv[55];
int main() {
  inv[0] = inv[1] = 1;
  for (int i = 2; i < 55; i++)
    inv[i] = (M - 1LL * (M / i) * inv[M % i] % M) % M;
  for (int i = 0; i <= 50; i++) {
    c[i][0] = 1;
    for (int j = 1; j <= i; j++) c[i][j] = (c[i - 1][j] + c[i - 1][j - 1]) % M;
  }
  dp[1][0][0] = 1;
  for (int i = 2; i <= 50; i++)
    for (int j = 1; j <= i / 2; j++)
      for (int k = 0; k < 2; k++) {
        for (int x = 1; i - 1 - x > 0; x++) {
          for (int y1 = 0; y1 <= j - k; y1++)
            for (int p1 = 0; p1 < 2; p1++)
              if (dp[x][y1][p1]) {
                int y2 = j - k - y1;
                for (int p2 = 0; p2 < 2; p2++)
                  if (dp[i - 1 - x][y2][p2]) {
                    if (max(y1 - p1 + 1 + y2, y2 - p2 + 1 + y1) == j) {
                      add(dp[i][j][k], 1LL * c[i - 2][x - 1] % M *
                                           dp[x][y1][p1] % M *
                                           dp[i - 1 - x][y2][p2] % M);
                    }
                  }
              }
        }
        add(dp[i][j][k], dp[i - 1][j - k][j - k - (j - 1)] % M);
        dp[i][j][k] = 1LL * i * dp[i][j][k] % M;
      }
  int n, k;
  while (cin >> n >> k) {
    int ans = (dp[n][k][0] + dp[n][k][1]) % M;
    ans = 1LL * ans * inv[n] % M;
    cout << ans << endl;
  }
}
