n,s,k=map(int,input().split());mod=10**9+7
for i in range(n):
	s-=k*i
if s<0:
	print(0)
else:
	dp=[[0]*(s+1) for i in range(n+1)]
	dp[0][0]=1
	for i in range(1,n+1):
		c=n-i+1
		x=[0]*c
		for j in range(s+1):
			x[j%c]+=dp[i-1][j];x[j%c]%=mod
			dp[i][j]+=x[j%c]
			dp[i][j]%=mod

	print(dp[n][s])