var f,g:text;
    p,x,y,z,i,nr:longint;
begin
     assign(f,'fact.in'); reset(f);
     assign(g,'fact.out'); rewrite(g);
     read(f,p);  x:=0;
     if p<0 then x:=0;
     if p=0 then x:=1;
     if p>0 then
     begin
          x:=p*5;     z:=5;
          repeat
          begin
               nr:=0;  z:=5;
               while x div z<>0 do
               begin
                    nr:=nr+x div z;
                    z:=z*5;
               end;
               x:=x-5;
          end
          until nr=p;
          x:=x+5;
     end;
     if x=0 then write(g,'-1')
            else write(g,x);
     close(g);
end.