import std.algorithm, std.array, std.container, std.range, std.bitmanip;
import std.numeric, std.math, std.bigint, std.random;
import std.string, std.conv, std.stdio, std.typecons;

void main()
{
  auto n = readln.chomp.to!int;
  auto pi = primes(n + 100);

  writeln(iota(n - 100, n + 101).find!(a => a >= 2 && !pi.canFind(a)).front);
}

int[] primes(int n)
{
  auto sieve = new bool[](n + 1);
  sieve[0..2] = false;
  sieve[2..$] = true;

  auto max = n.to!real.sqrt.to!int;
  foreach (p; 2..max + 1)
    if (sieve[p])
      foreach (q; iota(p * 2, n + 1, p))
        sieve[q] = false;

  return sieve.enumerate
    .filter!(a => a[1])
    .map!(a => a[0].to!int).array;
}