计算：3e(r/\.J6T:r
（1+3+5+……+1989）-（2+4+6+……+1988）3e(r/\.J6T:r
算式：提示;~;L)A9~*V5h5o'D6[3e(r/\.J6T:r
=:u/j(j0[3e(r/\.J6T:r