用Python制作掷硬币工具

import random
import os

a = input("请输入掷硬币次数：")
try:  #判断输入是否为整数
    a = int(a)
    if a > 0: #判断输入是否为正数
        zz = 0
        zf = 0
        ff = 0
        count = 0
        print("------------------------开始掷硬币------------------------")
        while count < a:
            b = random.randrange(1, 5)
            if b == 1:
                print("正正")
                zz = zz + 1
            elif b == 2 or b == 3:
                print("正反")
                zf = zf + 1
            else:
                print("反反")
                ff = ff + 1
            count = count + 1
        print("------------------------掷硬币结束------------------------")
        print("结果：正正有", zz, "次，正反有", zf, "次，反反有", ff, "次")
        os.system("pause")
    else:
        print("请输入正数！")
        os.system("pause")
except ValueError:
    print("请输入整数！")
    os.system("pause")