import sys
import math
from collections import deque
import copy
import bisect

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