Problem Description

For any positive integer $x$, let $g(x)$ be the number of its divisors. For example, $g(1)=1$, $g(6)=4$.

If a positive integer $x$ satisfies: $\forall 0 \lt i \lt x$, we have $g(x) \gt g(i)$, then $x$ is called an anti-prime number. For example, $1,2,4,6,12,24$ are all anti-prime numbers.

Now given a positive integer $N$, can you find the largest anti-prime number not exceeding $N$?

Input Format

A single line with a positive integer $N$.

Output Format

A single line with a positive integer, representing the largest anti-prime number not exceeding $N$.

1000

840

Hint

For all testdata, $1 \leq N \leq 2 \times 10^9$.

Translated by ChatGPT 5