import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.regex.Pattern;


class SumOfDigits {
    
    public static void main(String...args) throws IOException {
        BufferedReader reader =
                new BufferedReader(new InputStreamReader(System.in));
        Pattern pattern = Pattern.compile("\\s+");
        String line;
        
        for (line = reader.readLine(); ; line = reader.readLine()) {
            String[] splitted = pattern.split(line);
            int n = Integer.valueOf(splitted[0]);
            int m = Integer.valueOf(splitted[1]);
            
            if (n == -1 && m == -1) {
                return;
            }
            
            int sum = 0;
            
            for (int i = n; i <= m; i++) {
                sum += computeSum(i);
            }
            
            System.out.println(sum);
        }
    }

    private static int computeSum(int i) {
        int sum = 0;
        
        do {
            sum += i % 10;
            i = i / 10;
        } while (i != 0);
        
        return sum;
    }
    
}