var nr,z,p,i:longint;
		f:text;
begin
  assign(f,'fact.in');reset(f);
	read(f,p);
  assign(f,'fact.out');rewrite(f);
  z:=0;i:=0;
  while z < p do
  	begin
      inc(i,5);
      pu:=5;
      r:=0;
      while i div pu>0 do
   			begin
		     	inc(r,i div pu);
		      pu := pu * 5;
		    end;
      inc(z,r);
    end;
  if z>p then
  	writeln(f,-1)
  else if p = 0 then
  	writeln(f,1)
  else
	  writeln(f,i);
  close(f);
end.