Alex and the Steak

Time limit1sMemory limit1024 MB

Summary

Given k presses of a microwave button, where each group of five presses adds 30, 60, 90 and so on seconds per press, find the total heating time.

Level: Easy2 of 10
Topics: Implementation, Math
Solved: No attempts yet

Problem

Lion Alex is a predator, and predators eat only meat. Alex, however, has lived his whole life in a zoo, so instead of raw meat he eats steaks heated in a microwave oven.

The microwave Alex uses has only one button. The button sets how long the food will be heated. Each press adds a fixed number of seconds to the current heating time. The first five presses add 30 seconds each, the next five add 60 seconds each, the next five add 90 seconds each, and so on. Each group of five presses adds 30 seconds more per press than the group before it.

Alex pressed the button $k$ times. Find how many seconds his steak will be heated.

Input

The only line of the input contains a natural number $k$ , the number of times Alex pressed the button.

Output

Print one number, the number of seconds the steak will be heated.

Examples2

Example 1
Input
```
3
```
Expected output
```
90
```
Example 2
Input
```
7
```
Expected output
```
270
```