//By BLADEVIL

var

    n                                   :int64;

    prime                               :array[..] of longint;

    mindiv                              :array[..] of longint;

    i, j                                :longint;

    ansnum, ansx                        :int64;

procedure dfs(d,p,sum,ans:int64);

var

    i                                   :longint;

begin

    if sum>n then exit;

    if (ans>ansnum) or (ans=ansnum) and (sum<ansx) then

    begin

        ansx:=sum;

        ansnum:=ans;

    end;

    if(sum*prime[d]>n) then exit;

    dfs(d,p+,sum*prime[d],ans+ans div (p+));

    dfs(d+,,sum*prime[d+],ans*);

end;

begin

    read(n);

    if n= then

    begin

        writeln();

        halt;

    end;

    for i:= to  do

    begin

        if mindiv[i]= then

        begin

            inc(prime[]);

            prime[prime[]]:=i;

            mindiv[i]:=i;

        end;

        for j:= to prime[] do

        begin

            if prime[j]*i> then break;

            mindiv[i*prime[j]]:=prime[j];

            if i mod prime[j]= then break;

        end;

    end;

    dfs(,,,);

    writeln(ansx);

end.