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

ulong MAX = 1_000_100, MOD = 1_000_000_007, INF = 1_000_000_000_000;
alias sread = () => readln.chomp();
alias lread(T = long) = () => readln.chomp.to!(T);
alias aryread(T = long) = () => readln.split.to!(T[]);
alias Pair = Tuple!(long, "a", long, "b");
alias PQueue(T, alias less = "a<b") = BinaryHeap!(Array!T, less);

void main()
{
    auto x = lread();
    bool prime;
    while(!prime)
    {
        if(x.isPrime)
            prime = true;
        
        x++;
    }
    writeln(x - 1);
}

bool isPrime(long x)
{
    auto limit = cast(long) sqrt(cast(real) x).floor();
    bool ret = true;
    foreach (i; iota(2, limit))
    {
        if(!(x % i))
        {
            ret = false;
            break;
        }
    }
    return ret;
}

void scan(TList...)(ref TList Args)
{
    auto line = readln.split();
    foreach (i, T; TList)
    {
        T val = line[i].to!(T);
        Args[i] = val;
    }
}
