F:=FreeGroup("R1","R2","R3","P");
R1:=F.1; R2:=F.2; R3:=F.3; P:=F.4;
G:=F/[P*R3*P^-1*R1^-1, P*R1*P^-1*R1*R2^-1*R1^-1, P^4,R2*R3^-1*R2^-1*R1^-1*R2*R3*R2^-1*R1,P^2*R2*R3^-1*R2^-1*R1^-1*R2*R3*R2^-1*R1*P^-2*R1^-1*R2*R3^-1*R2^-1*R1*R2*R3*R2^-1,(P^-1*R1)^3,(R1)^10,(P*R1)^15];