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