SP18932 SUMPRIM2 - Sum of primes (reverse mode)

XerK had prepared his new problem with some sums of primes up to some bounds. His results are well here, but he forgot the bounds. Your task is to find which was the last prime in the sum. This problem is extremely simple, but you have to be extremely fast.

The lonely line of input contains an integer **_S_**.

You have to print the last prime **_P_** such that **_sum(prime from 2 to P) = S_**.