N,S,K = [int(x) for x in input().split()]
S -= K*N*(N-1)//2
if S<0:
    print(0)
    exit()
dp = [[[0 for k in range(S+1)] for j in range(N)] for i in range(S+1)]
for i in range(S+1):
    dp[i][0][i] = 1
for i in range(S+1):
    for j in range(1,N):
        for k in range(i+1):
            for l in range(k+1):
                dp[i][j][k] += dp[i-k][j-1][l]
total = 0
for i in range(S+1):
    # print(total)
    total += dp[S][N-1][i]
print(total)
# print('S = ',  S)