请教关于LINGO的問題。急求代码。

MODEL: SETS: QUARTERS/1,2,3,4/:DEM,RP,OP,INV; ENDSETS MIN=@SUM(QUARTERS:400*RP+450*OP+20*INV); @FOR(QUARTERS(I):RP(I)40); @FOR(QUARTERS(I)|I#GT#1: INV(I)=INV(I-1)+RP(I)+OP(I)-DEM(I);); INV(1)=10+RP(1)+OP(1)-DEM(1); DATA: DEM=40,60,75,25; ENDDATA END运行得：Objective value: 78450.00