http://www.cnblogs.com/CXCXCXC/p/5093584.html

//By SiriusRen

#include <cstdio>

using namespace std;

int n,m,K,mod=1000000007,f[33][33][666][9];

int main(){

    scanf("%d%d%d",&n,&m,&K);

    f[1][0][0][0]=1;

    for(int i=1;i<=n;i++)

        for(int j=0;j<=m;j++)

            for(int k=0;k<1<<(K+1);k++){

                for(int l=0;l<K;l++){

                    (f[i][j][k][l+1]+=f[i][j][k][l])%=mod;

                    if(i-K+l>0)(f[i][j+1][k^(1<<l)^(1<<K)][l]+=f[i][j][k][l])%=mod;

                }

                if(!(k&1))(f[i+1][j][k>>1][0]+=f[i][j][k][K])%=mod;

            }

    printf("%d\n",f[n+1][m][0][0]);

}