lingo改错,写的程序怎么运行不出来

lingo改错,写的程序怎么运行不出来
MODEL:
SETS:
location/1..12/:x,y,r;
ENDSETS
DATA:
x=0,8.20,0.50,5.70,0.77,2.87,4,43,2.58,0.72,9.76,3.19,0.55;
y=0,0.50,4.90,5.00,6.49,8.76,3.26,9.32,9.96,3.16,7.20,7.88;
r=600,1000,800,1400,1200,700,600,800,1000,1200,1000,1100;
ENDDATA
min=@sum(location(i):(r(i)*((a-x(i))^2+(b-y(i))*2)^(1/2)));
END