COCI '13 Contest 3 #5 Parovi

View as PDF

Submit solution


Points: 12 (partial)
Time limit: 1.0s
Memory limit: 64M

Problem type

The distance between two integers is defined as the sum of the absolute result of subtracting their digits. For example, the distance between the numbers 4561 and 3278 is |43|+|52|+|67|+|18|=12. If one of the numbers consists of fewer digits than the other, we fill it with leading zeroes. Therefore, the distance between the numbers 32 and 5678 is |05|+|06|+|37|+|28|=21.

You are given two integers A and B. Calculate the sum of distances between each pair of numbers belonging in the interval [A,B].

Input Specification

The first and only line of input contains integers A, B (1AB1050000).

Output Specification

The first and only line of output must contain the required number from the text. Given that the number could be extremely large, output the answer modulo 1000000007.

Scoring

In test cases worth 20% of total points, A and B will not exceed 10000.

In test cases worth 40% of total points, A and B will not exceed 10100.

Sample Input 1

Copy
1 5

Sample Output 1

Copy
40

Sample Input 2

Copy
288 291

Sample Output 2

Copy
76

Explanation for Sample Output 2

The distances are, respectively, (288,289)=1,(288,290)=9,(288,291)=8,(289,290)=10,(289,291)=9,(290,291)=1. Each of them counts twice, which is in total 2×(1+9+8+10+9+1)=76.

Sample Input 3

Copy
1000000 10000000

Sample Output 3

Copy
581093400

Comments

There are no comments at the moment.