x1,x2,x3,x4
-x2,x1-x2,x3,x4
-x1+x2,-x1,x3,x4
x2,x1,-x3,-x4
x1-x2,-x2,-x3,-x4
-x1,-x1+x2,-x3,-x4
-x1,-x2,-x3,-x4
x2,-x1+x2,-x3,-x4
x1-x2,x1,-x3,-x4
-x2,-x1,x3,x4
-x1+x2,x2,x3,x4
x1,x1-x2,x3,x4
