x1,x2,x3,x4,x5,x6,x7,x8,x9,x10,x11,y1,y2,y3,y4,y5,y6,y7,y8,y9,y10,y11
x1*y1-1
y1*x1-1
x2*y2-1
y2*x2-1
x3*y3-1
y3*x3-1
x4*y4-1
y4*x4-1
x5*y5-1
y5*x5-1
x6*y6-1
y6*x6-1
x7*y7-1
y7*x7-1
x8*y8-1
y8*x8-1
x9*y9-1
y9*x9-1
x10*y10-1
y10*x10-1
x11*y11-1
y11*x11-1
Free_group_11