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

N, S, K = mapint()
mod = 10**9 + 7
if ((N - 1)*N//2)*K > S:
    print(0)
    exit()
else:
    S -= ((N - 1)*N//2)*K

# dp[i][j] j の i 分割
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>=0:
            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[-1][-1])