解题思路：
统计字符的直方图，输出直方图中不为0的个数

s = input()
#print(type(s))
#print(s)

len_s = len(s)
#print('len_s=',len_s)

L = list();
for i in range(128):
    #print(i)
    L.append(0)
#print(L)

for i in range(len_s):    
    #print(s[i],ord(s[i]),chr(ord(s[i])))
    if ord(s[i])>=0 & ord(s[i])<=127:
        L[ord(s[i])] += 1 
#print(L)

sum = 0
for i in range(128):
    if L[i]>0:
        sum += 1
print(sum)