Python :

# coding=utf-8
# 快速模幂计算函数
def mod_exp(a, b, mod):
    result = 1
    base = a % mod
    while b > 0:
        if b % 2 == 1:  # 如果b是奇数
            result = (result * base) % mod
        base = (base * base) % mod
        b //= 2
    return result

# 输入
a, b = map(int, input().split())

# 计算 a^b % 1000
last_three_digits = mod_exp(a, b, 1000)

# 输出最后三位数字，并补零
print(f"{last_three_digits:03d}")