#include<iostream>
using namespace std;
#include<vector>
    /* This function calculates (a^b)%MOD */
    long long pow(int a, int b, int MOD)
    {
        long long x=1,y=a;
        while(b > 0)
        {
            if(b%2 == 1)
            {
                x=(x*y);
                if(x>MOD) x%=MOD;
            }
            y = (y*y);
            if(y>MOD) y%=MOD;
            b /= 2;
        }
        return x;
    }

    /*  Modular Multiplicative Inverse
        Using Euler's Theorem
        a^(phi(m)) = 1 (mod m)
        a^(-1) = a^(m-2) (mod m) */
    long long InverseEuler(int n, int MOD)
    {
        return pow(n,MOD-2,MOD);
    }

    long long C(int n, int r, int MOD)
    {
         if(r<=0||r>n) return 1;
        vector<long long> f(n,1);
        for (int i=2; i<=n;i++)
            f[i]= (f[i-1]*i) % MOD;
        return (f[n]*((InverseEuler(f[r], MOD) * InverseEuler(f[n-r], MOD)) % MOD)) % MOD;
    }

main()
{

      long long n=1,k=1,l,tmp;
      while(n!=0&&k!=0)
      {
                       cin>>n>>k;
                       l=k+1;
                       if(l%2==0)
                       {
                          tmp= 2* pow( C(n-2,(l/2)-1,1000000007),2,1000000007);
                       }
                       else
                           tmp=2*C(n-2,(l-1)/2,1000000007)*C(n-2,(l-3)/2,1000000007);
                       cout<<tmp<<"\n";
      }
      return 0;
}