(1-13)*(2-4)((1+13)*2)-4(2*(1+13))-4(2-4)*(1-13)(2*(13+1))-4(4-2)*(13-1)4/(2/(13-1))(4/2)*(13-1)4*((13-1)/2)(4*(13-1))/2(13-1)/(2/4)((13-1)/2)*4((13+1)*2)-4(13-1)*(4-2)((13-1)*4)/2(13-1)*(4/2)
(1+13)*2-4=24