Acceleration

Time Limit: 1 sec

**The Problem**

One day** Faisal **was learning about Acceleration. He was reading...

**Acceleration** may be two types. Such as- **uniform acceleration** and **non-uniform acceleration**.

If the rate of increase of velocity of a moving body in a particular direction is maintained constant all the time, then the acceleration is said to be **uniform**.

Conversely, if the rate of increase of velocity changes with time, the acceleration is said to be** non-uniform** or variable.

The Velocity of a car decreases uniformly from **X ms-1** and after **T** **s** it becomes **Y ms-1**. Now he wanted to find the **Acceleration** of the car.

**The Input**

The input file contains 3 integers **X,** **Y **(-100 <=X, Y <=100) and **T **(**0 **<= **T **<= 200).

**The Output**

For each line of input print the value of **Acceleration **in a separated line.

**Sample Input**

25 5 4

**Sample Output**

-5

Problem Setter: Shaquib Mahmud

Special thanks to Samia Safa Ahmed