#include<iostream>
#include<fstream>
using namespace std;
ifstream f("2sah.in");
ofstream g("2sah.out");
int n,i,j,m[1001][1001],t,k,s,x,y;
int main()
{
    f>>t;
    f>>n>>k;
    m[1][n+1]=1;
    for(i=2;i<=n+1;i++)
        for(j=1;j<=2*n+1;j++)
        {
            if(j!=1&&j!=2*n+1) m[i][j]=m[i-1][j-1]+m[i-1][j]+m[i-1][j+1];
            else
            {
                if(j==1) m[i][j]=m[i-1][j]+m[i-1][j+1];
                if(j==2*n+1) m[i][j]=m[i-1][j-1]+m[i-1][j];
            }
        }
    if(t==1)
    {
        s=0;
        for(i=1;i<=2*n+1;i++)
            s=s+m[k][i];
        g<<s;
    }
    if(t==2)
    {
        x=1;
        y=k;
        s=0;
        while((x<=n+1)&&(y<=2*n+1))
        {
            s=s+m[x][y];
            x++;
            y+=2;
        }
        g<<s;
    }
    f.close();
    g.close();
    return 0;
}