tekrarlananReqemler

num = int(input())

arr =[]
count = 0

while num:
    arr.append(num%10)
    num//=10


c = 0
while c<len(arr):
    check = False
    j=1

    while j<len(arr):
        if arr[c] == arr[j]:
            del arr[j]
            check = True
        else:
            j+=1
    del arr[c]
    if check:
        count+=1

print(count)