Problem J1: Next in line

Problem DescriptionCopy Anchor Link

You know a family with three children. Their ages form an arithmetic sequence: the difference in ages between the middle child and youngest child is the same as the difference in ages between the oldest child and the middle child. For example, their ages could be 5, 10 and 15, since both adjacent pairs have a difference of 5 years.

Given the ages of the youngest and middle children, what is the age of the oldest child?

Input SpecificationCopy Anchor Link

The input consists of two integers, each on a separate line. The first line is the age $Y$ of the youngest child ($0 \leq Y \leq 50$). The second line is the age $M$ of the middle child ($Y \leq M \leq 50$).

Output SpecificationCopy Anchor Link

The output will be the age of the oldest child.

Sample Input 1Copy Anchor Link

12
15

Output for Sample Input 1Copy Anchor Link

18

Sample Input 2Copy Anchor Link

10
10

Output for Sample Input 4Copy Anchor Link

10