題目描述
The number S is called the mean of two numbers R1 and R2 if S is equal to (R1+R2)/2. Mirko's birthday present for Slavko was two integers R1 and R2. Slavko promptly calculated their mean which also happened to be an integer but then lost R2! Help Slavko restore R2.
輸入輸出格式
輸入格式：
The first and only line of input contains two integers R1 and S, both between -1000 and 1000.
輸出格式：
Output R2 on a single line.
輸入輸出樣例
輸入樣例#1： 11 15
輸出樣例#1： 19
輸入樣例#2： 4 3
輸出樣例#2： 2
c++
#include<iostream>
using namespace std;
int main()
{
int r1,r2,s;
cin>>r1>>s;
r2=s*2-r1;
cout<<r2;
return 0;
}
Python
# -*- coding: utf-8 -*-
num = input().split()
r1 = num[0]
s = num[1]
r2 = int(s)*2 - int(r1)
print(r2)