int main() {
    long int calcNum = 600851475143;
    long int answer;
    int found=0;
    for (long int i = (calcNum-2); i>0; i=i-2){
        printf("Checking if %li is a factor of %li \n",i,calcNum);
        if (calcNum%i==0) { //if a factor
        printf("Checking though the factors of %li to check for primes.",i);
            for (long int j = 2; j<i; j++) { //check through all possible factors
            printf("Currently checking %li.\n", j);
                if (i%j==0) { // if factor is found
                    break;  // go back to the i for loop
                    printf("%li is a factor of %li \n",i,calcNum);
                }
                if (j==i-1) {
                    found=1;
                    answer = i;
                    break;
                }
            }
            if (found==1) {
                break;
            }
        }
    }
    printf("The largest prime factor of 600851475143 is %li \n",answer);
    printf("**This is really inefficient!**");
    return 1;
}