user: You are a structured reasoning expert tasked with solving problems step by step. 
You first think about the reasoning process in the mind and then provide the answer. The reasoning process and answer should be enclosed within <think> </think> and <answer> </answer> tags, respectively, i.e., <think> reasoning process here </think> <answer> answer here </answer>. 
Given a question and the associated knowledge graph triplets (entity, relation, entity), you are asked to answer the question with these triplets and your own knowledge. 
You can break down the original question into several sub-questions and explore the given knowledge graph to solve them step-by-step. If there are multiple possible answers, choose one as the final answer. 
After thinking, when you finally reach a conclusion, clearly state the answer within <answer> </answer> tags, i.e., <answer> answer here </answer>. 
Question: what kind unit of length is associated with a measurement system whose mass units include picul? 
Knowledge Triplets: Chinese units of measurement, measurement_unit.measurement_system.weight_units, Tael
Picul, measurement_unit.mass_unit.measurement_system, Chinese units of measurement
picul.noun.01, base.wordnet.synset.hypernym, weight unit.noun.02
Mass, measurement_unit.dimension.units, Atomic mass unit
Mass, measurement_unit.dimension.units, Planck mass
Chinese units of measurement, measurement_unit.measurement_system.weight_units, Mace
Mass, measurement_unit.dimension.si_base_unit, Kilogram
m.0t081jw, type.object.permission, m.019h
Mass, measurement_unit.dimension.units, Mace
Chinese units of measurement, measurement_unit.measurement_system.weight_units, Catty
Li, measurement_unit.distance_unit.measurement_system, Chinese units of measurement
weight unit.noun.02, base.wordnet.synset.hyponymy, picul.noun.01
Chinese units of measurement, measurement_unit.measurement_system.weight_units, Cash
Mace, measurement_unit.mass_unit.measurement_system, Chinese units of measurement
Mass, measurement_unit.dimension.units, Tael
Mass, base.schemastaging.context_name.pronunciation, g.125_l6gm1
Mass, measurement_unit.dimension.units, MeV/c²
Mass, measurement_unit.dimension.units, Grain
Mass, measurement_unit.dimension.units, Dram
Candareen, measurement_unit.mass_unit.measurement_system, Chinese units of measurement
Mass (Physics), base.skosbase.skos_concept.equivalent_topic, Mass
Mass, measurement_unit.dimension.units, Ounce
Ana Marie Cox, base.yupgrade.user.topics, Mass
Wired, base.yupgrade.user.topics, Mass
Chinese units of measurement, measurement_unit.measurement_system.weight_units, Candareen
Mass, measurement_unit.dimension.units, Earth mass
Mass, measurement_unit.dimension.units, Long ton
g.125_q7_ls, base.schemastaging.pronunciation.yomigana, たん
Mass, measurement_unit.dimension.units, Troy ounce
Mass, measurement_unit.dimension.units, Carat
Mass, measurement_unit.dimension.units, Stone
picul.noun.01, base.wordnet.synset.lexname, noun.quantity
m.07vn7ph, base.yupgrade.user.topics, Mass
Chinese units of measurement, measurement_unit.measurement_system.length_units, Cun
Mass, base.skosbase.vocabulary_equivalent_topic.equivalent_concept, Mass (Physics)
m.019h, type.permission.controls, m.0t081jw
m.07nfbgl, base.ontologies.ontology_instance_mapping.freebase_topic, Mass
Mass, base.ontologies.ontology_instance.equivalent_instances, m.07nfbgl
Chinese units of measurement, measurement_unit.measurement_system.weight_units, Picul
m.0qplrls, dataworld.gardening_hint.last_referenced_by, Mass
Chinese units of measurement, measurement_unit.measurement_system.length_units, Li
m.07s3ffv, base.wordnet.word_sense.sense, picul.noun.01
Mass, measurement_unit.dimension.units, Electron rest mass
Mass, measurement_unit.dimension.units, Hundredweight
Mass, measurement_unit.dimension.units, Cental
Mass, measurement_unit.dimension.units, Microgram
Chinese units of measurement, user.movgp0.default_domain.measurement_system.unit_of_lenght, Li
m.0tj44mw, dataworld.gardening_hint.last_referenced_by, m.0t081jw
Mass, measurement_unit.dimension.units, Solar mass
Mass, measurement_unit.dimension.units, Pennyweight
Picul, base.schemastaging.context_name.pronunciation, g.125_q7_ls
Cash, measurement_unit.mass_unit.measurement_system, Chinese units of measurement
m.075_7gq, base.yupgrade.user.topics, Mass
Mass, measurement_unit.dimension.units, Tonne
picul.noun.01, base.wordnet.synset.equivalent_topic, Picul
Catty, measurement_unit.mass_unit.measurement_system, Chinese units of measurement
m.0t081jw, dataworld.gardening_hint.last_referenced_by, Picul
Mass, measurement_unit.dimension.units, Kilogram
Mass, measurement_unit.dimension.units, Milligram
mass.noun.01, base.wordnet.synset.equivalent_topic, Mass
Tael, measurement_unit.mass_unit.measurement_system, Chinese units of measurement
Cun, measurement_unit.distance_unit.measurement_system, Chinese units of measurement
noun.quantity, base.wordnet.lexical_name.synsets, picul.noun.01
Mass, measurement_unit.dimension.units, Cash
Mass, measurement_unit.dimension.units, Picul
Mass, measurement_unit.dimension.units, Jupiter mass
Mass, user.avh.default_domain.ellerdale_topic.ellerdale_id, 0080-0198
Picul, measurement_unit.measurement_system.weight_units, Chinese units of measurement
Mass, measurement_unit.dimension.units, Short quarter
Chinese units of measurement, measurement_unit.distance_unit.measurement_system, Cun
Mass, measurement_unit.dimension.units, Catty
Mass, measurement_unit.dimension.units, Gram
Picul, measurement_unit.mass_unit.weightmass_in_kilograms, 60.478982
Mass, measurement_unit.dimension.units, Short ton
Mass, measurement_unit.dimension.units, Pound
picul.noun.01, base.wordnet.synset.syntactic_category, Noun
picul.noun.01, base.wordnet.synset.word, m.07s3ffv
Mass, measurement_unit.dimension.units, Troy pound
Mass, measurement_unit.dimension.units, Candareen
Mass, measurement_unit.dimension.units, Planetary mass
Mass, measurement_unit.dimension.units, Long quarter

Answer: Cun
Li