"""

https://yukicoder.me/problems/no/269

0,K,2K, ... , (N-1)K
を引いておけばok

"""

import sys
from sys import stdin

N,S,K = map(int,stdin.readline().split())

mod = 10**9+7

S -= (N-1)*K*N //2

if S < 0:
    print (0)
    sys.exit()

P = [[0] * (N+1) for i in range(S+1)]

for i in range(S+1):

    for j in range(N+1):

        if i == j == 0:
            P[i][j] = 1
        elif j == 0:
            P[i][j] = 0
        elif i-j >= 0:
            P[i][j] = P[i][j-1] + P[i-j][j]
        else:
            P[i][j] = P[i][j-1]

        P[i][j] %= mod

print (P[-1][-1])