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