#include<stdio.h>
#define I int
I n,s,k,f[101][20001],M;I main(I N){scanf("%d%d%d",&n,&s,&k);s-=k*n*(n-1)/2;f[0][0]=1;for(;N<=n;N++)for(M=0;M<=s;M++)f[N][M]=((M<N?0:f[N][M-N])+f[N-1][M])%1000000007;N=!printf("%d\n",f[n][s]);}