这个怎么做，python

练习题2:统计字符串中str='abdf1234'字母的个数
提示:Python循环采用
for i in range(4),那么i依次为0，1，2，3函数语法
range(start,stop[, step])
参数说明:
start:计数从start开始。默认是从0开始。例range (5）等价于range (0，5);
stop:计数到stop结束，但不包括stop。例如: range (0，5)是[0,1,2,3,4]没有5step:步长，默认为1。例如: range (0. 5)等价于range(0,5,1)

count=0
s='advsd123asd'
for i in range(len(s)):
   if (s[i] >= 'a' and s[i] <= 'z') or (s[i] >= 'A' and s[i] <= 'Z'):
    count+=1
print(count)

a='abcd1234'
count = 0
for i in range(len(a)):
    if a[i].isalpha():
        count+=1
print(count)

# 统计一个字符串中字母、数字及其他字符的个数，返回一个元组

def tongji(s):
    count1 = 0
    count2 = 0
    count3 = 0
    for i in range(len(s)):
        if (s[i] >= 'a' and s[i] <= 'z') or (s[i] >= 'A' and s[i] <= 'Z'):
            count1 = count1 + 1
        elif (s[i] >= '0' and s[i] <= '9'):
            count2 = count2 + 1
        else:
            count3 = count3 + 1
    return (count1,count2,count3)

s = input("请输入一个字符串:")
print(tongji(s))