var
	fi, fo : text;
  p : longint;
  p5, n5, s, d, m : int64;
begin
	assign(fi,'fact.in'); reset(fi);
  assign(fo,'fact.out'); rewrite(fo);
  read(fi,p);
  s := 1; d := 2124967900;
  repeat
    n5 := 0; p5 := 5; m := (s+d) div 2;
  	while p5 <= m do
    	begin
        n5 := n5+m div p5;
    		p5 := p5*5;
      end;
    if n5 < p then
    	s := m+1
    else
    	d := m-1;
  until n5 = p;
  while m mod 5 <> 0 do
  	dec(m);
  write(fo,m);
  close(fi); close(fo);
end.

1320(5) = 125 + 75 + 10 = 210
            1 +  5 + 25

                        5
    5    5    5    5    5
55555555555555555555555555 32 de factori de 5

    5
555555555