华为笔试题1，62.5%,为啥有3个没过呢？

import sys
while 1:
    # 读取第一行的n
    n = input()
    flag=0
    li = n.split(',')
    i=0
    if len(li)>100:
        print("error.0001")
        break
    while i<len(n):
        if 'a'<=n[i]<='z'&nbs***bsp;'A'<=n[i]<='Z'&nbs***bsp;n[i]==',':
            i+=1
        else:
            flag=-1
            break
    for i in range(len(li)):
        if flag==-1: break
        tmp=li[i]
        if len(tmp)<3:
            flag=-1
            break
        if not 'A'<=tmp[0]<='Z':
            flag=-1
            break
        for j in range(1,len(tmp)):
            if not 'a'<=tmp[j]<='z':
                flag=-1
                break

    if flag==-1:
        print("error.0001")
        break

    dic={}
    n=len(li)
    for i in range(n):
        if li[i] not in dic:
            dic[li[i]]=1
        else:
            dic[li[i]]+=1
    maxd = li[0]
    res =[maxd]
    # print(dic)
    for i, v in dic.items():
        if dic[i]>dic[maxd]:
            maxd=dic[i]
        if dic[i]==dic[maxd]:
            res.append(i)
    res.sort()
    print(res[0])
    break