#include <bits/stdc++.h>
using namespace std;
const int maxn = 57;
const int MOD = 1e9 + 7;
const int inv2 = 500000004;
int c[maxn][maxn];
int n, k;
long long dp[maxn][maxn][2];
long long mod(long long x) {
  if (x >= MOD) return x % MOD;
  return x;
}
int main() {
  c[0][0] = 1;
  for (int i = 1; i <= 50; i++) {
    c[i][0] = c[i][i] = 1;
    for (int j = 1; j < i; j++) {
      c[i][j] = mod(c[i - 1][j - 1] + c[i - 1][j]);
    }
  }
  scanf("%d%d", &n, &k);
  if (k > n / 2) {
    printf("0\n");
    return 0;
  }
  dp[1][0][0] = dp[0][0][1] = 1;
  for (int i = 1; i <= n; i++) {
    for (int j = 0; j <= k; j++) {
      for (int l = 0, r = i - 1; l <= r; l++, r--) {
        for (int k = 0; k <= j; k++) {
          long long res = 1;
          res = c[i - 1][l];
          if (l == r) res = mod(res * inv2);
          if (l)
            res = mod(mod(res * l) * r);
          else
            res = mod(res * r);
          dp[i][j][0] =
              mod(dp[i][j][0] + mod(mod(dp[l][k][1] * dp[r][j - k][1]) * res));
          if (k < j) {
            dp[i][j][1] =
                mod(dp[i][j][1] +
                    mod(mod(dp[l][k][1] * dp[r][j - k - 1][0]) * res));
            dp[i][j][1] =
                mod(dp[i][j][1] +
                    mod(mod(dp[l][k][0] * dp[r][j - k - 1][1]) * res));
            dp[i][j][1] =
                mod(dp[i][j][1] +
                    mod(mod(dp[l][k][0] * dp[r][j - k - 1][0]) * res));
          }
        }
      }
    }
  }
  printf("%d\n", mod(dp[n][k][0] + dp[n][k][1]));
  return 0;
}
