x13+900*x23+700*x33+400*x43+1000*x14+800*x24+700*x34+500*x44-7900-50*(x13+x23+x33+x43+x14+x24+x34+x44); x11<=3; x11>=1; x12>=2; x12<=5; x13=2; x14>=1; x14<=2; x21>=2; x22>=2; x23>=2; x24>=2; x24<=8; x31>=2; x32>=2; x33>=2; x34>=1; x41>=1; x42>=3; x43>=1; x44=0;

x11+x12+x13+x14<=9; x21+x22+x23+x24<=17; x31+x32+x33+x34<=10; x41+x42+x43+x44<=5; x11+x21+x31+x41<=10; x12+x22+x32+x42<=16; x13+x23+x33+x43<=11; x14+x24+x34+x44<=18; end