var p,x,i,ii:longint;
    f,g:text;
begin
assign(f,'fact.in');
reset(f);
readln(f,p);
Close(f);
assign(g,'fact.out');
rewrite(g);
x:=0;
i:=0;
if p=0 then
 writeln(g,1) else begin
while x<p do
   begin
   inc(i,5);
   ii:=i;
      while ii mod 5=0 do
        begin
           inc(x);
           ii:=ii div 5;
        end;
        end;
   if x>p then writeln(g,-1) else
        writeln(g,i);
        end;
		Close(g);
end.