Sum of Primes

Given an integer n, your task is to compute the sum of all prime numbers less than n using the Sieve of Eratosthenes algorithm.

A prime number is a natural number greater than 1 that has no positive divisors other than 1 and itself. Formally, if we let \(P\) be the set of all prime numbers less than \(n\), then you must compute \(\sum_{p \in P} p\).

If n is less than or equal to 2, the answer is 0.

inputFormat

The input consists of a single integer n provided on a line (read from STDIN).

outputFormat

Output a single integer – the sum of all prime numbers less than n (printed to STDOUT).

## sample

10

17

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