begin
integer i,j,k
ownintegerarray a(0:19)=10,9,8,7,6,5,4,3,2,1,0-1,-2,-3,-4,-5,-6,-7,-8,-9,-10;
                                              ! 0-1, not 0, -1 !!
j=4
for k=0,1,19 cycle
write(a(k)//4,4); write(a(k)//j,4);  newline
repeat
endofprogram