import core.bitop, std.algorithm, std.ascii, std.bigint, std.conv, std.math,
    std.functional, std.numeric, std.range, std.stdio, std.string, std.random,
    std.typecons, std.container, std.format;

// dfmt off
T lread(T = long)(){return readln.chomp.to!T();}
T[] aryread(T = long)(){return readln.split.to!(T[])();}
void scan(TList...)(ref TList Args){auto line = readln.split();
foreach (i, T; TList){T val = line[i].to!(T);Args[i] = val;}}
alias sread = () => readln.chomp();enum MOD = 10 ^^ 9 + 7;
alias PQueue(T, alias less = "a<b") = BinaryHeap!(Array!T, less);
// dfmt on

void main()
{
    long X = lread();
    while (true)
    {
        long l = factorize(X).length;
        if (l == 1)
        {
            writeln(X);
            return;
        }
        X++;
    }
}

/// 素因数分解
long[] factorize(long x)
{
    assert(0 < x, "x is negative");
    long[] result;
    while ((x & 1) == 0)
    {
        x /= 2;
        result ~= 2;
    }
    for (long i = 3; i * i <= x; i += 2)
        while (x % i == 0)
        {
            x /= i;
            result ~= i;
        }
    if (x != 1)
        result ~= x;
    return result;
}
