分解质因数

import math

def prime(n):
    if n <= 1:
        return False
    if n == 2:
        return True
    i = 2
    while i <= math.sqrt(n):
        if n % i == 0:
            return False
        i += 1
    return True
a = []
for i in range(2, 100):
    if prime(i):
        a.append(i)

temp = int(input("请输入一个数："))
flag = False
print(temp, "=", end=" ")
i = 0
while temp > 1:
    if temp % a[i] == 0:
        if flag:
            print("*", end="")
        else:
            flag = True
        print(a[i], end="")
        temp /= a[i]
    else:
        i += 1