import std.stdio,
       std.conv,
       std.string,
       std.range,
       std.math,
       std.algorithm;

void main()
{
    auto N = readln.strip.to!int;

    foreach (x; max(2, N - 100).iota(N + 101))
    {
        foreach (y; 2.iota(x))
        {
            if (x % y == 0)
            {
                x.writeln;
                return;
            }
        }
    }
}