백준 1929번(Java)

import java.io.*;
import java.util.*;

public class Main {

	public static boolean[] prime;
	
	public static void main(String[] args) throws IOException{
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringTokenizer st = new StringTokenizer(br.readLine());
		StringBuilder sb = new StringBuilder();
		
		int m = Integer.parseInt(st.nextToken());
		int n = Integer.parseInt(st.nextToken());
		prime = new boolean[n+1];
		get_prime();
		
		for(int i=m; i<=n; i++) {
			if(!prime[i])
				sb.append(i).append('\n');
		}
		
		System.out.println(sb);
	}
	
	// true:소수X, false:소수
	public static void get_prime() {
		prime[0] = prime[1] = true;
		
		for(int i=2; i<Math.sqrt(prime.length); i++) {
			if(prime[i]) continue;
			
			for(int j=i*i; j<prime.length; j += i) {
				prime[j] = true;
			}
		}
	}
}