Practice Arithmetic with the exercise "Crazy List"

Learning Opportunities

This puzzle can be solved using the following concepts. Practice using these concepts and improve your skills.

Arithmetic

Statement

Goal

The Crazy List Machine produces crazy lists of integers. Each time the Crazy Machinist creates a new crazy list, he chooses an initial value. Then, he chooses as many crazy operators as he wants and apply all of them on the last value of the crazy list to calculate next value. He repeats the crazy operators application (all the operators with the same order) growing the crazy list until his coffee machine rings.

Each crazy operator can be :
- Add/Subtract an integer number
- Multiply by an integer number

Examples:
Start with 1 and apply operator +3 at each iteration will give the crazy list

1 4 7 10 13 ...

Start with 2 and apply operators +1, x3, -1, x2 at each iteration will give the crazy list

2 16 100 604 3628 ...

When the Crazy Machinist gives you a list he created, you have to predict the next number (the uniqueness of such next number is guaranteed).

Input

Line 1: A list of integers separated by spaces

Output

Line 1: The prediction of the next number

Constraints

Example

Input

1 4 7 10

Output

Solve it

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