def countttttt():
    n=list(input())
    d={}
    for i in n:
        if ord(i)<0 or ord(i)>127:
            continue
        else:
            if d.get(i) is not None:
                pass
            else:
                d[i]=1
    l1=list(d.keys())
    print(len(l1))
countttttt()