file = open('16.txt')
text = file.readline()
text = text.strip()
d = dict()
Max = 0
Min = 10000000000000
for c in text:
    if c in d:
        d[c] += 1
        Max = max(Max, d[c])
    else:
        d[c] = 1
for elem in d:
    Min = min(Min, d[elem])
print(Max - Min)