program factorial;
var f,g:text;
    k,l,p,k2:longint;
begin
assign(f,'fact.in'); reset(f);
assign(g,'fact.out'); rewrite(g);
readln(f,p);
l:=0;k:=0;
while l<p do
          begin
          k:=k+5; k2:=k;
          while k2 mod 5=0 do
                           begin
                           inc(l);
                           k2:=k2 div 5;
                           end;
          end;
          if p=0 then k:=1;
if l<>p then
        writeln(g,'-1')
        else
writeln(g,k);
close(f); close(g);
end.