Python 代码
mod = 1000
def qmi(a, b, p):
res = 1
while b:
if b & 1:
res = res * a % p
a = a * a % p
b >>= 1
return res
k, x = map(int, input().split())
n = qmi(x, x, mod)
res = 1
for i in range(n-1, n-k, -1):
res = res * i
res = res // (n-i)
print(res)