ISBN 1-3-Sum

Interview

Time limit1sMemory limit128 MB

Summary

Given the last three digits of an ISBN starting with 9780921418, compute the 1-3-sum and print it.

Level: Easy2 of 10
Topics: Math, Implementation, Simulation
Solved: No attempts yet

Problem

The International Standard Book Number (ISBN) is a 13-digit code that identifies a book. These codes have a special property that lets you detect whether the number was written down correctly.

The 1-3-sum of a 13-digit number is obtained by multiplying its digits alternately by 1 and 3 and then adding the results. Counting from the first digit, the odd-positioned digits are multiplied by 1 and the even-positioned digits by 3.

For example, the 1-3-sum of the number $9780921418948$ is computed as

$9\cdot1 + 7\cdot3 + 8\cdot1 + 0\cdot3 + 9\cdot1 + 2\cdot3 + 1\cdot1 + 4\cdot3 + 1\cdot1 + 8\cdot3 + 9\cdot1 + 4\cdot3 + 8\cdot1 = 120$

The special property of an ISBN is that its 1-3-sum is always a multiple of 10.

Write a program that computes the 1-3-sum of a 13-digit number. To reduce the amount of typing, you may assume that the first ten digits are always $9780921418$ , exactly as in the example above. Your program reads the last three digits and prints the 1-3-sum.

Input

The last three digits are given on three separate lines, one digit per line. Each digit is an integer between $0$ and $9$ inclusive.

Output

Print the 1-3-sum in the format The 1-3-sum is X, where X is the computed 1-3-sum.

Examples4

Example 1
Input
```
9
4
8
```
Expected output
```
The 1-3-sum is 120
```
Example 2
Input
```
0
0
0
```
Expected output
```
The 1-3-sum is 91
```
Example 3
Input
```
9
9
9
```
Expected output
```
The 1-3-sum is 136
```
Example 4
Input
```
1
2
3
```
Expected output
```
The 1-3-sum is 101
```