import std.stdio, std.string, std.conv, std.array, std.algorithm;
import std.uni, std.range, std.math, std.container, std.datetime;
import core.bitop, std.typetuple, std.typecons;

immutable long MOD = 1_000_000_007;
alias tie = TypeTuple;

void main(){
    auto N = readln.chomp.to!long;
    long p = 3;

    while(p^^2 <= N){
        if(N % p == 0){
            writeln(p);
            return;
        }
        ++p;
    }

    if(N == 4){
        writeln(4);
        return;
    }

    writeln(N % 2 ? N : N / 2);
}


void readVars(T...)(auto ref T args){
    auto line = readln.split;
    foreach(ref arg ; args){
        arg = line.front.to!(typeof(arg));
        line.popFront;
    }
    if(!line.empty){
        throw new Exception("args num < input num");
    }
}