30 50
BAA BDA BDD BDD BDD BDD BBA BBA BBA BBD BBD BBD BBD BBB BBB BBB BBB BBB BBB BBB BBB BBB BBB AA AA AA DA DA DD DD DD DD DD BA BA BD BD BD BB BB BB BB BB BB A D D B B B 
DDC CCC CCC ACC AAC AAA CCC DCC DDC CCC ACC AAC AAA CCC ACC AAC AAA DCC DAC DAA DDC DDA DDD CC DC BC CC BC CC AC AA BC BA CC DC CC AC AA CC AC AA DC DA DD C C A C A D