Sum of Primes

Given a non-negative integer n, your task is to compute the sum of all prime numbers less than n.

A prime number is defined as a natural number greater than 1 that has no positive divisors other than 1 and itself. In particular, note that if n \le 1, then n is not a prime number. To efficiently determine if a number is prime, you only need to check divisibility for integers up to \(\sqrt{n}\).

The formula for checking a prime is: for any integer \(x > 1\), if no integer \(d\) in the range \(2 \le d \le \sqrt{x}\) divides \(x\) evenly, then \(x\) is a prime.

inputFormat

The input consists of a single line containing one non-negative integer n.

outputFormat

Output a single integer which is the sum of all prime numbers less than n.

## sample

10

17

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