import PIL, math

#Problem 10 sum of primes
###INEFFICIENT###
#def isPrime(number):
#	if (number <=1):
#		return False
#	for i in range(2,number):
#		if(number%i==0):
#			return False
#	return True

#def prime_factors(number):
	#primes = []
	#for i in range(number, 2, -1):
		#if(number%i==0):
			#if (isPrime(i)):
				#return i
	#return primes



def prime_factors(number):
	primes = []
	if (number <=1):
		return [1]
	a = [1] * number
	a[0]=0
	a[1]=0#not prime
	for i in range(2,int(math.ceil(math.sqrt(number)))):
		if(a[i]==1):
			j = i**2 #cross out all the multiples
			while(j < number):
				a[j] = False
				j+=i
	
	for k in range(2, number):
		#is prime
		if(a[k]==1):
			primes.append(k)
	return primes

out = prime_factors(2000000)
print(str(sum(out)))