#915. Largest prime gap
You get n. Find the largest difference between two neighboring prime numbers that are not greater than n.
### Input
One integer n (3 ≤ n ≤ 10⁶).
### Output
A number.
Examples
Input
77664
Output
72
Input
676791
Output
114
💡 You can solve it with Python, JavaScript or blocks. Read the input line by line with input(). Don't print a question (like input("Number: ")). Print exactly what the output asks for, nothing more.