var p,n,zero,j:longint;

begin
n:=0;

assign(input,'fact.in'); reset(input);
readln(p);
while zero<p do
  begin
    n:=n+5;
    j:=n;
    while j mod 5 = 0 do
      begin
        zero:=zero+1;
        j:=j div 5;
      end;    
      

  end;


assign(output,'fact.out');  rewrite(output);
if((zero<>0) and (zero=p)) then writeln(n)
  else if zero>p then writeln('-1')
    else writeln('1');
close(output);
end.