Find R2

Time limit1sMemory limit128 MB

Summary
Given R1 and the average S of two integers, compute and print the other integer R2.
Level

Easy1 of 10

Topics
Math, Implementation
Solved
No attempts yet

Problem

The average S of two integers R1 and R2 is (R1 + R2) / 2.

Given R1 and the average S, find the second number R2.

Input

The first line contains two integers R1 and S, separated by a space.

Each number is between -1000 and 1000, inclusive.

Output

Print R2 on the first line.

Examples2

  1. Example 1

    Input
    11 15
    Expected output
    19

  2. Example 2

    Input
    4 3
    Expected output
    2