#include <bits/stdc++.h>
using namespace std;
int SNT(int n)
{
    if(n < 2) return 0;
    int dem = 0;
    for(int i = 2; i <= sqrt(n); i++)
    {
        if(n % i == 0)
            return 0;
    }
    return 1;
}


int main()
{
    int n, a, b;
    while(cin >> n)
    {
        a = -1000000000;
        for(int i = n; i >= 1; i--)
        {
            if(SNT(i) == 1)
            {
                a = i;
                break;
            }
        }
        for(int i = n; i<= n + 10000000; i++)
        {
            if(SNT(i) == 1)
            {
                b = i;
                break;
            }
        }
        if(n - a <= b - n)
            cout << a << endl;
        else cout << b << endl;
    }
}