P3sec.java

class P3sec
{
    public static void main(String[] a)
    {
         long numm = 600851475143l;
long newnumm = numm;
long largestFact = 0;
 
int counter = 2;
while (counter * counter <= newnumm) {
    if (newnumm % counter == 0) {
        newnumm = newnumm / counter;
        largestFact = counter;
    } else {
        counter++;
    }
}
if (newnumm > largestFact) { // the remainder is a prime number
    largestFact = newnumm;
}
System.out.println(largestFact);
    }
}