program factorial;
var n,p,aux,zero:integer;
begin
assign(input,'fact.in');
reset(input);
read(input,p);
close(input);
n:=0; zero:=0;
repeat
      n:=n+5;
      aux:=n;
      while aux mod 5=0 do begin
            aux:=aux div 5;
            inc(zero);
            end;
until zero>=p;
if p=0 then n:=1;
if zero>p then n:=-1;
assign(output,'fact.out');
rewrite(output);
write(output,n);
close(output);
end.