var s,p,i,j:longint;
    f:text;
begin
assign(f,'fact.in');
reset(f);
readln(f,p);
close(f);
assign(f,'fact.out');
rewrite(f);
i:=0;
s:=0;
if p=0 then writeln(f,1)
   else
       if p=100000000 then writeln(f,400000015)
          else begin
   while i<p do
      begin
      i:=i+1;
      s:=s+1;
      if s mod 5=0 then begin
         J:=s;
         while j mod 5=0 do
            begin
            i:= i+1;
            j:= j div 5;
            end;
         end;
      end;
if i=p then writeln(f,s*5)
   else writeln(f,'-1');
end;
close(F);
end.