/*************************************************************************
	> File Name: prime_number.cpp
	> Description: prime_number.cpp
	> Author: songtianlun
	> Mail: songtianlun@frytea.com 
	> Created Time: 2022-06-23 11:46:18
 ************************************************************************/

#include<iostream>
#include<math.h>
using namespace std;
static int num=100000000;
int main(){
 
       bool *array=new bool[num+1];
       array[0]=false;
       array[1]=false;
       for(int i=2;i<=num;i++) array[i]=true;
       int b=int(pow(num,0.5))+1;
       int index=0;
       for(int j=2;j<=b;j++){
                index=2*j;
                while(index<=num){
                        array[index]=false;
                        index+=j;
                }
       }
       delete array;
       cout<<endl<<"===========Done!==========="<<endl;
       return 0;
}