#include <iostream>
#include <iomanip>
#include <stdio.h>
#include <bits/stdc++.h>
#include <math.h>
#include <string>
#include <cstring>

using namespace std;
//#define PI 3.1415926
bool isprime[2000010]={0};
int zhishu(long long n)
{
    memset(isprime,true,sizeof(isprime));
    isprime[1] = false;

    for(int i = 2;i <= n;i++)
    {
        if(isprime[i])
        {
            for(int j = 2;j*i <= n;j++)
            {
                isprime[i*j] = false;
            }
        }
    }
    return 0;
}
int main()
{
long long n;
long long shuzu[10000010];
cin >> n;
zhishu(n);
for(int i = 1,j = 0;i <= n;i++)
{
    if(isprime[i])
    {
        shuzu[j] = i;//这个地方无法给shuzu完成赋值
        j+=1;
        cout << i <<endl;
        cout << shuzu[j] <<endl;
    }
}
return 0;
}