#include <iostream>

using namespace std;


int main(){
	long int a, b;
	unsigned long long int sum = 0;
	cin>>a>>b;
	int n;
	if(a%2 == 0) a++;
	if(b%2 == 0) b--;
	
	for(long int i=a; i<=b; i+=2){
		n = i;
		while(n>0){
			sum+=(n%10);
			n/=10;
		}
	}
	cout<<sum;
	return 0;
}