#include<stdio.h>
#include<math.h>
int main(){
int num,temp;
int max_digit=0,min_digit=9;
scanf("%d",&num);
temp=abs(num);
while(temp!=0){
int digit=temp%10;
if(digit>max_digit){
max_digit=digit;
}
if(digit<min_digit){
min_digit=digit;
}
temp/=10;
}
int a=max_digit-min_digit;
printf("%d\n",a);
return 0;
}