Problem Description. 

Nithin proposed to his girl friend on valentines day. But she had kept a condition that if he answers her task then she will accept his proposal. As Nithin is new to programming, help him in solving the task. Your task is so simple.i.e...you need to find the factorial of a given number.

Input
Input description.
An Integer N

Output
Output description.
Print the required output

Constraints
Should contain all the constraints on the input data that you may have. Format it like:

1 ≤ N ≤ 100

Example
Input:
5

Output:
120

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