program factoria;
var n,p,ft,k:longint ;f:text;
begin
        assign(f,'fact.in');
        reset(f);
        readln(f,p);
        close(f);
        ft:=0;
        repeat
                n:=n+1;
                k:=n;
                while k mod 5=0 do begin
                        ft:=ft+1;
                        k:=k div 5;
                        end;

        until ft=p;
        assign(f,'fact.out');
        rewrite(f);
        writeln(f,n);
        close(f);
end.