/**
 *
 * @author inoxor
 */

import java.io.*;

public class Assignment1 {
    public static void main(String[] args) {
        long timeBegin = System.nanoTime();
        int limit = 10000000;
        int primes = 0;
        
        boolean[] isPrime = new boolean[limit+1];   // initializes as false
        
        for(int i = 2; i*i <= limit; i++) {
            if(!isPrime[i]) {
                for(int j = i; j*i <= limit; j++)   // eliminate i^2 and multiples of it
                    isPrime[i*j] = true;            // we use true to mark non-primes
            }
        }
        
        PrintWriter out = null;
        
        try {
            out = new PrintWriter("primes.txt");    // printwriter does not flush by default
            
            for(int i = 2; i <= limit; i++) {
                if(!isPrime[i]) {
                    out.println(i);
                    primes++;
                }
            }
        } catch(IOException e) {
            System.out.println(e);
        } finally {
            if(out != null)
                out.close();    // flush & close
        }
        
        long estimatedTime = System.nanoTime() - timeBegin;
        System.out.println("Execution took " + estimatedTime/1000000 + " ms. Found " + primes + " primes.");
    }
}