#include<iostream>
#include<cstdio>
#include<cstring>
#include<string>
using namespace std;
const int MAXN = 1000000;
int prime[MAXN + 1];
void getPrime()
{
memset(prime, 0, sizeof(prime));
for (int i = 2; i <= MAXN; i++)
{
if (!prime[i])
{
prime[++prime[0]] = i;
}
for (int j = 1; j <= prime[0] && prime[j] <= MAXN / i; j++)
{
prime[prime[j] * i] = 1;
if (i % prime[j] == 0)
{
break;
}
}
}
}
int main()
{
int n;
getPrime();
while(~scanf("%d",&n))
{
int cnt=0,f=0;
for(int i=1;i<=MAXN;i++)
{
if(prime[i]>=n)
{
for(int j=1;j<MAXN;j++)
{
if(prime[j]==i)
{
cout<<prime[i]<<endl;
f=1;
break;
}
}
}
if(f)
break;
}
}
}