#include <iostream>
#include <vector>
#include <string>
using namespace std;


int sumdigits(int x){
    int ret=0;
    while(x){
        ret+=x%10;
        x/=10;
    }

    return ret;
}

long long sumdigstotal(int a, int b){
    long long total=0;

    while(a<=b && a%10!=0){
        total+=sumdigits(a);
        a++;
    }
    while(b>=a && b%10!=9){
        total+=sumdigits(b);
        b--;
    }
    
    if(b<=a) return total;
   
    long long pa=a/10, pb=b/10;
    //cout<<"totaling pa "<<pa<<" pb "<<pb<<'\n';
 
    total+=10*sumdigstotal(a/10,b/10);
    total+=45*(pb-pa+1);

    return total;
}

int main(){
    int a,b; 
    cin>>a>>b;

    if(a%2==0) ++a;
    if(b%2==0) --b;

    long long total=0;

    while(a<=b && a%10!=1){
        total+=sumdigits(a);
        a+=2;
    }
    while(b>=a && b%10!=9){
        total+=sumdigits(b);
        b-=2;
    }

    if(a>=b){ cout<<total<<'\n'; return 0; } 
    else{
    
        long long pa=a/10, pb=b/10;

        total += (1+3+5+7+9)*(pb-pa+1);

        long long subtotal=sumdigstotal(pa,pb);        

        //cout<<pa<<' '<<pb<<" subtotal "<<subtotal<<'\n';
 
        total+=5*subtotal;
        cout<<total<<'\n';
    }
}