BZOJ2729 [HNOI2012]排队

/**************************************************************
Problem: 2729
User: rausen
Language: Python
Result: Accepted
Time:708 ms
Memory:8736 kb
****************************************************************/

n, m = [int(st) for st in raw_input().split()]
fac = [1] * 2010
for i in range(1, 2010) : fac[i] = fac[i - 1] * i
def c(n, m) :
if (n < m): return 0
return fac
/ fac[n - m]
print c(n, n) * (c(n + 1, 2) * c(n + 3, m) + 2 * (n + 1) * c(n + 2, m - 1) * m)