Problem Statement
Given an integer N, find the sum of all primes < N.
Input Format
The only line of the input file contains a positive integer N.

Output Format
Output the sum of all primes < N.

Constraints
1 ≤ N ≤ 4000000
You are guaranteed that the answer will fit in a 64-bit integer.

SAMPLE INPUT
1000

SAMPLE OUTPUT
76127
from math import sqrt

def checkPrime(num):
    limit = int(sqrt(num))
    for i in range(2,limit+1):
        if num%i == 0:
            return False
    return True

def primeUsingSieve(N):
    arr = []
    i = 2
    while(i<=N):
        arr.append(i)
        i += 1
    limit = int(sqrt(N))
    for i in range(2,limit+1):
        if arr[i-2] == 0:
            continue
        else:
            incr = i
            num = i*2
            while(num<=N):
                arr[num-2] = 0
                num += incr
    return sum(arr)

N = int(raw_input())
print primeUsingSieve(N-1)