111 - Father Age

Father Age

Time Limit: 1 sec


The Problem

The average age of two children and their father is X years. The average age of these children and their mother is Y years. Mother's age is M years; what is the father's age?



if X = 17, Y = 13, and M = 25 then

Father's age is 37 years.




The Input

The input file contains only 3 integer numbers X, Y, M (X, Y, M<=50).


The Output

Output will show the one integer numbers which is father's age in a separate line.


Sample Input

17 13 25


Sample Output






Problem Setter: Shahin ShamS