var p,x,nr,nr2:longint;
    f,g:text;
begin
assign (f,'fact.in');
assign (g,'fact.out');
reset (f);
rewrite (g);
read(f,p);
nr:=0;
x:=0;
while x<p do
      begin
       nr:=nr+5;
       nr2:=nr;
       while nr2<>0 do
             begin
              if nr2 mod 5=0 then x:=x+1;
              nr2:=nr2 div 5;
             end;
      end;
if p=0 then write (g,0)
else
begin
if x=p then write (g,nr)
else
write (g,'-1');
end;
close (f);
close (g);
end.