import java.util.*;
import java.lang.*;
 
class Main
{
	public static void main (String[] args) throws java.lang.Exception
	{
 
	Scanner sc= new Scanner (System.in);
		do{
			int n1=sc.nextInt();
			int n2=sc.nextInt();
			if ((n1==-1) && (n2==-1)) { break; }
			if (n1==n2) {System.out.println(n1); continue;}
			System.out.println(sumOfDigitsFrom1ToN(n2)-sumOfDigitsFrom1ToN(n1-1));
		}while(true);
	}
 
	public static int sumOfDigitsFrom1ToN(int n){
		if (n<10) return n*(n+1)/2;
		int d=(int)Math.log10((double) n);
		int[] a = new int[d+1];
		a[0]=0;
		a[1]=45;
		for (int i=2;i<d+1;i++){
			a[i]=a[i-1]*10+45*(int) Math.ceil((double)Math.pow(10,i-1));
		}
		int p = (int)Math.ceil((double)Math.pow(10, d));
		int msd=n/p;
 
		return msd*a[d]+(msd*(msd-1)/2)*p+msd*(1+n%p) + sumOfDigitsFrom1ToN(n%p);
	}
}

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