mod=10**9+7
N,S,K=map(int, input().split())

n=S-N*(N-1)*K//2
m=N
M=mod

if n>=0:
    dp = [[0] * (n+1) for i in range(m+1)]
    dp[0][0]=1
    for i in range(1,m+1):
        for j in range(0,n+1):
            if j-i>=0:
                dp[i][j]=(dp[i-1][j]+dp[i][j-i])%M
            else:
                dp[i][j]=dp[i-1][j]%M
    print(dp[-1][-1])
else:
    print(0)