c1+c2+c3+c4
6 1 1 1
6 3 1 1
6 1 3 1
6 1 1 3
ri-r1,i=2,3,4
6 1 1 1
0 2 0 0
0 0 2 0
0 0 0 2
D = 6*2^3 = 48.