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?

Example:

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**

37

Problem Setter: Shahin ShamS