#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));
}