a[101][20001]={{1}};i,j,n,s;main(k){scanf("%d%d%d",&n,&s,&k);for(s-=n*(n-1)/2*k;++i<=n;)for(j=0;j<=s;j++)a[i][j]=(a[i-1][j]+(j<i?0:a[i][j-i]))%1000000007;i=!printf("%d",a[n][s]);}