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: who is the ravens coach? 
Knowledge Triplets: Baltimore Ravens at Cleveland Browns, 2008-11-02, american_football.football_game.receiving, m.079289p
Baltimore Ravens at New England Patriots, 2009-10-04, american_football.football_game.rushing, m.07p5w_p
Baltimore Ravens at Cleveland Browns, 2009-11-16, american_football.football_game.receiving, m.08nlcd6
Baltimore Ravens at San Diego Chargers, 2009-09-20, american_football.football_game.receiving, m.07mljs8
Baltimore Ravens at Indianapolis Colts, 2008-10-12, american_football.football_game.receiving, m.079211f
Baltimore Ravens at Pittsburgh Steelers, 2009-01-18, american_football.football_game.passing, m.0792dtd
Baltimore Ravens at Cleveland Browns, 2009-11-16, american_football.football_game.rushing, m.08nlchg
Baltimore Ravens at San Diego Chargers, 2009-09-20, american_football.football_game.receiving, m.07mljhk
Baltimore Ravens at New England Patriots, 2010-01-10, american_football.football_game.receiving, m.09rls8c
Baltimore Ravens at San Diego Chargers, 2009-09-20, american_football.football_game.receiving, m.07mljq2
Baltimore Ravens at Dallas Cowboys, 2008-12-20, american_football.football_game.receiving, m.0793ck3
Baltimore Ravens at New York Giants, 2008-11-16, american_football.football_game.receiving, m.07921yz
Baltimore Ravens at San Diego Chargers, 2009-09-20, american_football.football_game.receiving, m.07mljgg
Baltimore Ravens at Pittsburgh Steelers, 2009-01-18, american_football.football_game.receiving, m.0792dw6
Baltimore Ravens at Pittsburgh Steelers, 2009-01-18, american_football.football_game.receiving, m.07923sq
Baltimore Ravens at San Diego Chargers, 2009-09-20, american_football.football_game.passing, m.07mljkv
Baltimore Ravens at New England Patriots, 2009-10-04, american_football.football_game.receiving, m.07p5x1q
Baltimore Ravens at Cleveland Browns, 2008-11-02, american_football.football_game.receiving, m.079288x
John Harbaugh, american_football.football_coach.current_team_head_coached, Baltimore Ravens
Baltimore Ravens at New England Patriots, 2010-01-10, american_football.football_game.rushing, m.09rls69
Baltimore Ravens at Cleveland Browns, 2009-11-16, american_football.football_game.receiving, m.08nlcf4
Baltimore Ravens at New York Giants, 2008-11-16, american_football.football_game.receiving, m.07921zh
Baltimore Ravens at Pittsburgh Steelers, 2008-09-29, american_football.football_game.receiving, m.0792bjl
Baltimore Ravens at Cleveland Browns, 2009-11-16, american_football.football_game.receiving, m.08nlck8
Baltimore Ravens at New England Patriots, 2010-01-10, american_football.football_game.passing, m.09rlsb2
Baltimore Ravens at Cleveland Browns, 2009-11-16, american_football.football_game.receiving, m.08nlcdp
Baltimore Ravens at Pittsburgh Steelers, 2009-01-18, american_football.football_game.passing, m.07923p2
m.062_hj0, american_football.football_historical_coach_position.team, Baltimore Ravens
Baltimore Ravens at Pittsburgh Steelers, 2008-09-29, american_football.football_game.receiving, m.07920rr
Baltimore Ravens at San Diego Chargers, 2009-09-20, american_football.football_game.receiving, m.07mljc1
Baltimore Ravens at Pittsburgh Steelers, 2009-01-18, american_football.football_game.receiving, m.0792dwk
Baltimore Ravens at Indianapolis Colts, 2008-10-12, american_football.football_game.receiving, m.0792123
Baltimore Ravens at New York Giants, 2008-11-16, american_football.football_game.receiving, m.07921_4
Baltimore Ravens at New England Patriots, 2010-01-10, american_football.football_game.passing, m.09rls5w
John Harbaugh, people.person.profession, American Football coach
Baltimore Ravens at New England Patriots, 2009-10-04, american_football.football_game.receiving, m.07p5wxg
Baltimore Ravens at New England Patriots, 2009-10-04, american_football.football_game.rushing, m.07p5wvd
Baltimore Ravens at Pittsburgh Steelers, 2009-12-27, american_football.football_game.receiving, m.09kngf0
m.011w_zjc, sports.sports_team_coach_tenure.team, Baltimore Ravens
Baltimore Ravens at New York Giants, 2008-11-16, american_football.football_game.receiving, m.0793g15
Baltimore Ravens at Cleveland Browns, 2008-11-02, american_football.football_game.receiving, m.07921l7
Baltimore Ravens at Cleveland Browns, 2008-11-02, american_football.football_game.rushing, m.07921hr
Baltimore Ravens at New England Patriots, 2010-01-10, american_football.football_game.rushing, m.09rlsbj
Baltimore Ravens at San Diego Chargers, 2009-09-20, american_football.football_game.receiving, m.07mljcr
m.0_r0s7v, american_football.football_historical_coach_position.team, Baltimore Ravens
Baltimore Ravens at Cleveland Browns, 2009-11-16, american_football.football_game.receiving, m.08nlcbt
Baltimore Ravens at San Diego Chargers, 2009-09-20, american_football.football_game.receiving, m.07mljr7
Baltimore Ravens, american_football.football_team.current_head_coach, John Harbaugh
Baltimore Ravens at Cleveland Browns, 2008-11-02, american_football.football_game.receiving, m.07921kk
Baltimore Ravens at Cleveland Browns, 2008-11-02, american_football.football_game.rushing, m.0792877
Baltimore Ravens at Cleveland Browns, 2008-11-02, american_football.football_game.rushing, m.07921jh
Baltimore Ravens at Dallas Cowboys, 2008-12-20, american_football.football_game.passing, m.07922vh
Baltimore Ravens at New England Patriots, 2010-01-10, american_football.football_game.receiving, m.09rlscx
Baltimore Ravens, sports.sports_team.sport, American football
Baltimore Ravens at Indianapolis Colts, 2008-10-12, american_football.football_game.receiving, m.0792j8g
Baltimore Ravens at Pittsburgh Steelers, 2008-09-29, american_football.football_game.receiving, m.0792bhs
Baltimore Ravens at Cleveland Browns, 2008-11-02, american_football.football_game.receiving, m.07928b1
Baltimore Ravens, american_football.football_team.historical_coaching_staff, m.062_hht
m.062_hj0, american_football.football_historical_coach_position.coach, Rex Ryan
m.0nhrhj_, sports.sports_team_coach_tenure.coach, Jim Caldwell
Baltimore Ravens at Cleveland Browns, 2009-11-16, american_football.football_game.receiving, m.08nlccv
Baltimore Ravens at New England Patriots, 2009-10-04, american_football.football_game.receiving, m.07p5x10
Baltimore Ravens at New England Patriots, 2009-10-04, american_football.football_game.receiving, m.07p5x0c
Baltimore Ravens at New England Patriots, 2009-10-04, american_football.football_game.rushing, m.07p5w_b
Baltimore Ravens at Indianapolis Colts, 2008-10-12, american_football.football_game.receiving, m.0792112
Baltimore Ravens at San Diego Chargers, 2009-09-20, american_football.football_game.receiving, m.07mljql
Baltimore Ravens at Cleveland Browns, 2008-11-02, american_football.football_game.passing, m.07921gw
Baltimore Ravens, common.topic.image, Baltimore Ravens
Baltimore Ravens, american_football.football_team.conference, American Football Conference
Baltimore Ravens at San Diego Chargers, 2009-09-20, american_football.football_game.receiving, m.07mljrq
Baltimore Ravens at Indianapolis Colts, 2008-10-12, american_football.football_game.passing, m.07920zt
Baltimore Ravens at New England Patriots, 2010-01-10, american_football.football_game.rushing, m.09rlsck
Baltimore Ravens at Cleveland Browns, 2009-11-16, american_football.football_game.receiving, m.08nlckz
Baltimore Ravens at Dallas Cowboys, 2008-12-20, american_football.football_game.passing, m.0793cc_
Baltimore Ravens at New York Giants, 2008-11-16, american_football.football_game.receiving, m.0792207
Baltimore Ravens at New York Giants, 2008-11-16, american_football.football_game.receiving, m.0793g09
m.062_hjj, american_football.football_historical_coach_position.team, Baltimore Ravens
Baltimore Ravens at San Diego Chargers, 2009-09-20, american_football.football_game.receiving, m.07mljt0
Baltimore Ravens at San Diego Chargers, 2009-09-20, american_football.football_game.receiving, m.07mljdj
Baltimore Ravens at Pittsburgh Steelers, 2009-12-27, american_football.football_game.receiving, m.09kng89
Baltimore Ravens at Pittsburgh Steelers, 2008-09-29, american_football.football_game.receiving, m.07920sl
Baltimore Ravens at Pittsburgh Steelers, 2009-01-18, american_football.football_game.receiving, m.0792dym
Baltimore Ravens at Pittsburgh Steelers, 2009-01-18, american_football.football_game.receiving, m.07923vw
Baltimore Ravens at New York Giants, 2008-11-16, american_football.football_game.receiving, m.0793fzj
m.062_hj8, american_football.football_historical_coach_position.team, Baltimore Ravens
Baltimore Ravens at Pittsburgh Steelers, 2009-12-27, american_football.football_game.receiving, m.09kngdb
Baltimore Ravens at Pittsburgh Steelers, 2009-01-18, american_football.football_game.receiving, m.0792dxl
Baltimore Ravens at Cleveland Browns, 2008-11-02, american_football.football_game.receiving, m.079288k
Baltimore Ravens at New England Patriots, 2010-01-10, american_football.football_game.receiving, m.09rls80
Baltimore Ravens at Green Bay Packers, 2009-12-07, american_football.football_game.passing, m.098jnth
Steve Bisciotti, sports.sports_team_owner.teams_owned, Baltimore Ravens
Baltimore Ravens at New England Patriots, 2009-10-04, american_football.football_game.receiving, m.07p5x1c
Baltimore Ravens at Pittsburgh Steelers, 2008-09-29, american_football.football_game.receiving, m.0792bfk
Baltimore Ravens at New England Patriots, 2009-10-04, american_football.football_game.receiving, m.07p5x2w
Baltimore Ravens at Pittsburgh Steelers, 2009-01-18, american_football.football_game.receiving, m.0792dxy
Baltimore Ravens at Cleveland Browns, 2009-11-16, american_football.football_game.passing, m.08nlcgv
Baltimore Ravens at Dallas Cowboys, 2008-12-20, american_football.football_game.receiving, m.0793cgh
Baltimore Ravens at Cleveland Browns, 2009-11-16, american_football.football_game.passing, m.08nlc80
Baltimore Ravens, american_football.football_team.division, AFC North
Baltimore Ravens at Pittsburgh Steelers, 2009-12-27, american_football.football_game.receiving, m.09kngc_
Baltimore Ravens at Green Bay Packers, 2009-12-07, american_football.football_game.passing, m.098jn_d
Baltimore Ravens at Pittsburgh Steelers, 2008-09-29, american_football.football_game.receiving, m.07920s5
Baltimore Ravens at Cleveland Browns, 2009-11-16, american_football.football_game.rushing, m.08nlc8m
Baltimore Ravens at Pittsburgh Steelers, 2009-01-18, american_football.football_game.receiving, m.0792dwx
Baltimore Ravens at New England Patriots, 2009-10-04, american_football.football_game.rushing, m.07p5x00
Baltimore Ravens at Cleveland Browns, 2008-11-02, american_football.football_game.rushing, m.079286v
Baltimore Ravens at Pittsburgh Steelers, 2008-09-29, american_football.football_game.receiving, m.0792bh4
Baltimore Ravens at New England Patriots, 2009-10-04, american_football.football_game.receiving, m.07p5wx3
Baltimore Ravens at New England Patriots, 2010-01-10, american_football.football_game.receiving, m.09rlsd7
m.062_hht, american_football.football_historical_coach_position.coach, Rex Ryan
Baltimore Ravens at Dallas Cowboys, 2008-12-20, american_football.football_game.receiving, m.0793ckm
Baltimore Ravens at New England Patriots, 2010-01-10, american_football.football_game.receiving, m.09rls91
Baltimore Ravens at New York Giants, 2008-11-16, american_football.football_game.receiving, m.0793fz1
Baltimore Ravens, american_football.football_team.historical_coaching_staff, m.062_hjj
Baltimore Ravens at Houston Texans, 2008-11-09, american_football.football_game.passing, m.07921m9
Baltimore Ravens at New York Giants, 2008-11-16, american_football.football_game.passing, m.0793fwt
Baltimore Ravens at Pittsburgh Steelers, 2009-01-18, american_football.football_game.receiving, m.07923w8
m.062_hht, american_football.football_historical_coach_position.team, Baltimore Ravens
Baltimore Ravens, american_football.football_team.historical_coaching_staff, m.062_hj8
Baltimore Ravens at New England Patriots, 2009-10-04, american_football.football_game.rushing, m.07p5ws_
Baltimore Ravens at San Diego Chargers, 2009-09-20, american_football.football_game.receiving, m.07mljj7
m.062_hj8, american_football.football_historical_coach_position.coach, Rex Ryan
Baltimore Ravens at Pittsburgh Steelers, 2009-01-18, american_football.football_game.receiving, m.0792dx7
Baltimore Ravens, american_football.football_team.away_games, Mile High Miracle
Baltimore Ravens at New England Patriots, 2010-01-10, american_football.football_game.rushing, m.09rls7b
Baltimore Ravens, sports.sports_team.coaches, m.0nhrhj_
Baltimore Ravens at Indianapolis Colts, 2008-10-12, american_football.football_game.receiving, m.079212g
m.0n_xsm9, american_football.football_historical_coach_position.team, Baltimore Ravens
Baltimore Ravens at New England Patriots, 2009-10-04, american_football.football_game.receiving, m.07p5wzj
Baltimore Ravens, american_football.football_team.current_head_coach, John Harbaugh
Baltimore Ravens at Indianapolis Colts, 2008-10-12, american_football.football_game.passing, m.0792j4h
Baltimore Ravens at Pittsburgh Steelers, 2008-09-29, american_football.football_game.receiving, m.0792bg6
Baltimore Ravens at Pittsburgh Steelers, 2009-01-18, american_football.football_game.receiving, m.07923vc
Baltimore Ravens at New England Patriots, 2009-10-04, american_football.football_game.receiving, m.07p5ww2
m.0_r0s7v, american_football.football_historical_coach_position.coach, Ted Marchibroda
Baltimore Ravens at New England Patriots, 2010-01-10, american_football.football_game.receiving, m.09rls9d
Baltimore Ravens at Cleveland Browns, 2009-11-16, american_football.football_game.receiving, m.08nlcc4
Baltimore Ravens at Cleveland Browns, 2008-11-02, american_football.football_game.rushing, m.07921j3
m.062_hjj, american_football.football_historical_coach_position.coach, Rex Ryan
Baltimore Ravens at San Diego Chargers, 2009-09-20, american_football.football_game.receiving, m.07mljfm
Baltimore Ravens at Pittsburgh Steelers, 2009-12-27, american_football.football_game.passing, m.09kng64
Baltimore Ravens at New England Patriots, 2009-10-04, american_football.football_game.receiving, m.07p5x2j
Baltimore Ravens at Cleveland Browns, 2008-11-02, american_football.football_game.rushing, m.0792884
Baltimore Ravens at New England Patriots, 2010-01-10, american_football.football_game.receiving, m.09rls9r
Baltimore Ravens at San Diego Chargers, 2009-09-20, american_football.football_game.receiving, m.07mljf1
Baltimore Ravens at New York Giants, 2008-11-16, american_football.football_game.receiving, m.0793g0t
Baltimore Ravens at Pittsburgh Steelers, 2008-09-29, american_football.football_game.passing, m.07920nz
Baltimore Ravens at Cleveland Browns, 2008-11-02, american_football.football_game.rushing, m.079287r
Baltimore Ravens at Indianapolis Colts, 2008-10-12, american_football.football_game.receiving, m.0792j7g
Baltimore Ravens at Cleveland Browns, 2008-11-02, american_football.football_game.receiving, m.07921kx
m.0nhrhj_, sports.sports_team_coach_tenure.team, Baltimore Ravens
Baltimore Ravens at New York Giants, 2008-11-16, american_football.football_game.receiving, m.0793f_3
Baltimore Ravens at Pittsburgh Steelers, 2008-09-29, american_football.football_game.receiving, m.0792bk2
The Raven, common.topic.image, Paul Gustave Dore Raven1
Baltimore Ravens at San Diego Chargers, 2009-09-20, american_football.football_game.passing, m.07mlj62
Baltimore Ravens at Cleveland Browns, 2008-11-02, american_football.football_game.receiving, m.07921k6
Baltimore Ravens at Pittsburgh Steelers, 2009-12-27, american_football.football_game.receiving, m.09kng8n
Baltimore Ravens at Cleveland Browns, 2009-11-16, american_football.football_game.rushing, m.08nlc9g
Baltimore Ravens at Pittsburgh Steelers, 2008-09-29, american_football.football_game.passing, m.0792b9p
Baltimore Ravens at Cleveland Browns, 2009-11-16, american_football.football_game.receiving, m.08nlckm
Baltimore Ravens at Cleveland Browns, 2009-11-16, american_football.football_game.receiving, m.08nlcjy
Baltimore Ravens at Cleveland Browns, 2008-11-02, american_football.football_game.receiving, m.0792898
Baltimore Ravens at Pittsburgh Steelers, 2009-12-27, american_football.football_game.passing, m.09kngbj
Baltimore Ravens at New England Patriots, 2010-01-10, american_football.football_game.rushing, m.09rls6n
Baltimore Ravens at New England Patriots, 2009-10-04, american_football.football_game.receiving, m.07p5x21
Baltimore Ravens at Cleveland Browns, 2008-11-02, american_football.football_game.passing, m.079286c
Baltimore Ravens at Pittsburgh Steelers, 2009-12-27, american_football.football_game.receiving, m.09kng7z
Baltimore Ravens at New England Patriots, 2009-10-04, american_football.football_game.rushing, m.07p5wv1
Baltimore Ravens at New York Giants, 2008-11-16, american_football.football_game.receiving, m.07921_s
Baltimore Ravens at Cleveland Browns, 2009-11-16, american_football.football_game.receiving, m.08nlcfp
Baltimore Ravens at Cleveland Browns, 2009-11-16, american_football.football_game.passing, m.08nlcg3
Baltimore Ravens at San Diego Chargers, 2009-09-20, american_football.football_game.receiving, m.07mljvq
Baltimore Ravens, sports.sports_team.coaches, m.011w_zjc
Baltimore Ravens at Cleveland Browns, 2008-11-02, american_football.football_game.receiving, m.07928bn
Baltimore Ravens at Pittsburgh Steelers, 2009-12-27, american_football.football_game.receiving, m.09kng9b
Baltimore Ravens at New England Patriots, 2009-10-04, american_football.football_game.receiving, m.07p5wxt
Baltimore Ravens at Cleveland Browns, 2008-11-02, american_football.football_game.rushing, m.07921jw
Baltimore Ravens at Pittsburgh Steelers, 2008-09-29, american_football.football_game.receiving, m.07920r8
Baltimore Ravens at New England Patriots, 2010-01-10, american_football.football_game.receiving, m.09rlsdy
Baltimore Ravens at New England Patriots, 2010-01-10, american_football.football_game.receiving, m.09rlsdl
Baltimore Ravens at New England Patriots, 2009-10-04, american_football.football_game.receiving, m.07p5wy5
Baltimore Ravens at San Diego Chargers, 2009-09-20, american_football.football_game.passing, m.07mljjv
Baltimore Ravens at Pittsburgh Steelers, 2009-01-18, american_football.football_game.receiving, m.0792dy8
Baltimore Ravens at New York Giants, 2008-11-16, american_football.football_game.passing, m.07921v3
Baltimore Ravens at New England Patriots, 2010-01-10, american_football.football_game.rushing, m.09rlsc6
Baltimore Ravens at Houston Texans, 2008-11-09, american_football.football_game.passing, m.0792g7h
Baltimore Ravens at New England Patriots, 2009-10-04, american_football.football_game.receiving, m.07p5wws
Baltimore Ravens, american_football.football_team.historical_coaching_staff, m.062_hj0
Baltimore Ravens at Pittsburgh Steelers, 2008-09-29, american_football.football_game.receiving, m.0792bj6
Baltimore Ravens at Pittsburgh Steelers, 2009-01-18, american_football.football_game.receiving, m.07923tk
Baltimore Ravens at New England Patriots, 2009-10-04, american_football.football_game.passing, m.07p5wzx
Baltimore Ravens at Pittsburgh Steelers, 2009-12-27, american_football.football_game.receiving, m.09kng8_
Baltimore Ravens, american_football.football_team.historical_coaching_staff, m.0n_xsm9
Baltimore Ravens at New England Patriots, 2009-10-04, american_football.football_game.receiving, m.07p5wz5
Baltimore Ravens at Dallas Cowboys, 2008-12-20, american_football.football_game.receiving, m.079231s
Baltimore Ravens at Pittsburgh Steelers, 2008-09-29, american_football.football_game.receiving, m.07920sy
Baltimore Ravens at Pittsburgh Steelers, 2009-12-27, american_football.football_game.receiving, m.09kngdp
Baltimore Ravens at Pittsburgh Steelers, 2008-09-29, american_football.football_game.rushing, m.07920pf
Baltimore Ravens, american_football.football_team.historical_coaching_staff, m.0_r0s7v
Baltimore Ravens at New England Patriots, 2009-10-04, american_football.football_game.passing, m.07p5wsk
Baltimore Ravens at New York Giants, 2008-11-16, american_football.football_game.receiving, m.079220n
Baltimore Ravens at Cleveland Browns, 2008-11-02, american_football.football_game.rushing, m.07921hc
Baltimore Ravens at Pittsburgh Steelers, 2009-12-27, american_football.football_game.receiving, m.09kng9p
Baltimore Ravens, sports.professional_sports_team.owner_s, Steve Bisciotti
Baltimore Ravens at New England Patriots, 2009-10-04, american_football.football_game.receiving, m.07p5wwf
Baltimore Ravens at New England Patriots, 2010-01-10, american_football.football_game.receiving, m.09rls8q
Baltimore Ravens at Dallas Cowboys, 2008-12-20, american_football.football_game.receiving, m.0792303
Baltimore Ravens, common.topic.notable_types, American football team
Baltimore Ravens at New England Patriots, 2010-01-10, american_football.football_game.receiving, m.09rls7p
Baltimore Ravens at Cleveland Browns, 2009-11-16, american_football.football_game.receiving, m.08nlcch

Answer: John Harbaugh