%how many solutions
G=[1,5,7,0,8;0,0,6,0,7;0,0,0,0,-3;0,0,0,0,0]
H=[1,5,0,0;0,-1,4,0;0,0,10,-2]
I=[1,5,6,0;0,-1,4,0;0,0,0,0]