program factorial;
var f,g:text;
    p,n,i,o,cn,k:longint;
begin
assign(f,'fact.in');
assign(g,'fact.out');
reset(f);
rewrite(g);
read(f,p);
if (p=0)then write(g,1) else
   begin
        while (i<=p)do begin
              if (i>=p)then break;
              n:=n+5;
              o:=0;
              cn:=n;
              while (cn mod 5=0)do begin
                    o:=o+1;
                    cn:=cn div 5;
                    end;
              i:=i+o;
              if (i-o<p)and(p<i)then write(g,-1)else
                 if (i-o<=p)and(p=i)then begin
                    k:=1;
                    end else if (i-o=p)then begin
                        k:=1;
                        break;
                        end;
              if (i=p)then break;
              end;
        if (k=1)then write(g,n);
        end;
close(f);
close(G);
end.