abab

#include<bits/stdc++.h>
using namespace std;
int main(){
int a,b,sum=0;
cin>>a>>b;
while(a<=b){
int n = a;
while(n>0){
sum = sum+n%10;
n=n/10;
}
a = a+1;
}
cout<<sum;
return 0;
}