import sys
def input(): return sys.stdin.readline().strip()
def mapint(): return list(map(int, input().split()))
sys.setrecursionlimit(10**9)

N, S, K = mapint()
mod = 10**9 + 7

ksum = (K+K*(N-1))*(N-1)//2
if ksum>S:
    print(0)
    exit()

S -= ksum
# 分割数
dp = [[0]*(S+1) for _ in range(N+1)]
dp[0][0] = 1

for i in range(1, N+1):
    for j in range(S+1):
        if j>=i:
            dp[i][j] = dp[i][j-i] + dp[i-1][j]
        else:
            dp[i][j] += dp[i-1][j]
        dp[i][j] %= mod

# print(dp)
print(dp[N][S])