import sys
import math
from collections import deque
import copy

MOD = 10 ** 9 + 7
N, S, K = map(int, input().split())
if N*K*N/2 > S:
    print(0)
    sys.exit()
dp = [[0 for _ in range(S + 10)] for _ in range(N + 10)]
dp[0] = [0 for _ in range(S + 10)]
for i in range(S + 10):
    if i * K * N >= S + 5:
        break
    dp[0][i * K * N] = 1
for i in range(1, N):
    for l in range(S + 1):
        if l - K * (N - i) >= 0:
            dp[i][l] = (dp[i][l - (N - i)] + dp[i - 1][l - K * (N - i)]) % MOD
        elif l - (N - i) >= 0:
            dp[i][l] = dp[i - 1][l - K * (N - i)] % MOD
print(dp[N - 1][S]%MOD)