uses crt;
var f,g:text;
    p,n,nr:longint;
function nr5(i:longint):longint;
 begin
 if i mod 5=0 then nr5:=nr5(i div 5)+1
      else nr5:=0;
 end;
procedure fact(var nr,n:longint;i:longint);
 begin
 if nr<p then
    begin
     nr:=nr5(i)+nr;
     fact(nr,n,i+5);
    end
       else if nr=p then n:=i-5
           else n:=-1;
 end;
begin
clrscr;
assign(f,'fact.in');
reset(f);
read(f,p);
close(f);nr:=0;
fact(nr,n,5);
assign(g,'fact.out');
rewrite(g);
if p<>0 then writeln(g,n) else writeln(g,1);
close(g);
end.