var sol:array[1..40000000]of int64;
    s,i,ct,rez:longint;
    fi,fo:text;
procedure afla(s:integer);
begin
     for i:=1 to 3000000 do
        begin
             ct:=5;
             while ct<=i do
                begin
                     sol[i]:=sol[i]+trunc(i/ct);
                     ct:=ct*5;
                end;
             if sol[i]=s then begin rez:=i; exit; end;
        end;
end;
begin
     assign(fi,'fact.in'); reset(fi);
     assign(fo,'fact.out'); rewrite(fo);
     read(fi,s);
     afla(s);
     writeln(fo,rez);
     close(fi);
     close(fo);
end.