#include<iostream>
#include<math.h>
#include<stdlib.h>
using namespace std;
int reverse(int num)
{
int rev_num=0;
while(num>0)
{
rev_num= rev_num*10 + num%10;
num= num/10;
}
return rev_num;
}
bool isPrime(int num)
{
int flag=1;
if(num%2==0)
{
return false;
}
else
{
int limit= (int)(sqrt(num));
int denom= 3;
while(denom<=limit)
{
if(num%denom==0)
{
flag=0;
return false;
}
else denom+=2;
}
return true;
}
}
int main()
{
int num;
cin>>num;
int flag=0;
while(flag==0)
{
int rev_num = reverse(num);
if(num-rev_num ==0)
{
bool ans = isPrime(num);
if(ans== true)
{
cout<<num;
flag=1;
}
else num++;
}
else num++;
}
}