#include <stdio.h>
#include <math.h>

// The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17.

// Find the sum of all the primes below two million.

int main() {
    long long sum = 0;
    int primesCount = 0;
    int primes[10000] = {0};

    int i = 2;

    while(i < 2000000) {
        if(isPrime(i, primesCount, primes) == 1) {
            if(primesCount < 10000) {
                primes[primesCount] = i;
            }
            sum += i;
            primesCount++;
        }

        if(i == 2) {
            i = 3;
        } else {
            i = i + 2;
        }
    }

    printf("%d primes sum: '%lld'\n\n", primesCount, sum);

    return 1;
}

int isPrime(int number, int primesCount, int *primes) {
    int i;
    for(i = 0; i < primesCount; i++) {
        if(primes[i] != 0) {
            if(number % primes[i] == 0  && number != primes[i]) {
                return 0;
            }
        } else {
            break;
        }
    }

    for(i = 3; i < (int)sqrt(number) + 1; i = i + 2) {
        if(number % i == 0 && i != number) {
            return 0;
        }
    }

    return 1;
};