import sys
import math
from collections import deque,Counter
from sys import stdin

#sys.setrecursionlimit(10**7)

int1=lambda x: int(x)-1
stinput=lambda :stdin.readline()[:-1]
ii=lambda :int(stinput())
mi=lambda :map(int, stdin.readline().split())
li=lambda :list(mi())
mi1=lambda :map(int1, stdin.readline().split())
li1=lambda :list(mi1())
mis=lambda :map(str, stdin.readline().split())
lis=lambda :list(mis())

from collections import defaultdict
#d=defaultdict(int)
#d=defaultdict(lambda:1)

mod=10**9+7
Mod=998244353
INF=10**18
ans=0

s=[int(i) for i in input()]
print(max(s)-min(s))