<|im_start|>system
Please reason step by step, and put your final answer within \boxed{}.<|im_end|>
<|im_start|>user
Given the following CIF representation:
data_SiSe2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.7
_cell_length_b   10.7
_cell_length_c   10.7
_cell_angle_alpha   161.45
_cell_angle_beta   161.45
_cell_angle_gamma   26.35
_symmetry_Int_Tables_number   1
_chemical_formula_structural   SiSe2
_chemical_formula_sum   'Si2 Se4'
_cell_volume   123.85
_cell_formula_units_Z   2
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
loop_
 _atom_site_type_symbol
 _atom_site_label
 _atom_site_symmetry_multiplicity
 _atom_site_fract_x
 _atom_site_fract_y
 _atom_site_fract_z
 _atom_site_occupancy
  Si  Si4  1  0.0  0.72  0.21  1.0
  Si  Si5  1  0.0  0.0  0.0  1.0
  Se  Se0  1  0.72  0.0  0.67  1.0
  Se  Se1  1  0.0  0.0  0.95  1.0
  Se  Se2  1  0.72  0.0  0.75  1.0
  Se  Se3  1  0.0  0.0  0.88  1.0

What is the crystal system of this material?<|im_end|>
<|im_start|>assistant
Given the following CIF representation:
data_SiSe2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.7
_cell_length_b   10.7
_cell_length_c   10.7
_cell_angle_alpha   161.45
_cell_angle_beta   161.45
_cell_angle_gamma   26.35
_symmetry_Int_Tables_number   1
_chemical_formula_structural   SiSe2
_chemical_formula_sum   'Si2 Se4'
_cell_volume   123.85
_cell_formula_units_Z   2
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
loop_
 _atom_site_type_symbol
 _atom_site_label
 _atom_site_symmetry_multiplicity
 _atom_site_fract_x
 _atom_site_fract_y
 _atom_site_fract_z
 _atom_site_occupancy
  Si  Si4  1  0.0  0.72  0.21  1.0
  Si  Si5  1  0.0  0.0  0.0  1.0
  Se  Se0  1  0.72  0.0  0.67  1.0
  Se  Se1  1  0.0  0.0  0.95  1.0
  Se  Se2  1  0.72  0.0  0.75  1.0
  Se  Se3  1  0.0  0.0  0.88  1.0

What is the crystal system of this material?