data = { "天津":{  "南開區":{   "南開大學":{    "歷史系":{},    "文學系":{},    "英語系":{},   },   "科技大學":{    "計算機系":{},    "機器系":{},    "軟件系":{},   },   "理工大學":{    "數學系":{},    "化學系":{},    "物理系":{},   },  },  "武清區":{   "武清大學":{    "歷史系":{},    "文學系":{},    "英語系":{},   },   "武清科技大學":{    "計算機系":{},    "機器系":{},    "軟件系":{},   },   "武清理工大學":{    "數學系":{},    "化學系":{},    "物理系":{},   },  },  "北辰區":{   "北辰大學":{    "歷史系":{},    "文學系":{},    "英語系":{},   },   "北辰科技大學":{    "計算機系":{},    "機器系":{},    "軟件系":{},   },   "北辰理工大學":{    "數學系":{},    "化學系":{},    "物理系":{},   },  }, }, "河北":{  "保定市": {   "保定大學": {    "歷史系": {},    "文學系": {},    "英語系": {},   },   "保定科技大學": {    "計算機系": {},    "機器系": {},    "軟件系": {},   },   "保定理工大學": {    "數學系": {},    "化學系": {},    "物理系": {},   },  },  "秦皇島": {   "秦皇島大學": {    "歷史系": {},    "文學系": {},    "英語系": {},   },   "秦皇島科技大學": {    "計算機系": {},    "機器系": {},    "軟件系": {},   },   "秦皇島理工大學": {    "數學系": {},    "化學系": {},    "物理系": {},   },  },  "石家莊": {   "石家莊大學": {    "歷史系": {},    "文學系": {},    "英語系": {},   },   "石家莊科技大學": {    "計算機系": {},    "機器系": {},    "軟件系": {},   },   "石家莊理工大學": {    "數學系": {},    "化學系": {},    "物理系": {},   },  }, }, "河南":{  "鄭州市": {   "鄭州大學": {    "歷史系": {},    "文學系": {},    "英語系": {},   },   "鄭州科技大學": {    "計算機系": {},    "機器系": {},    "軟件系": {},   },   "鄭州理工大學": {    "數學系": {},    "化學系": {},    "物理系": {},   },  },  "南陽市": {   "南陽大學": {    "歷史系": {},    "文學系": {},    "英語系": {},   },   "南陽科技大學": {    "計算機系": {},    "機器系": {},    "軟件系": {},   },   "南陽理工大學": {    "數學系": {},    "化學系": {},    "物理系": {},   },  },  "登封市": {   "登封大學": {    "歷史系": {},    "文學系": {},    "英語系": {},   },   "登封科技大學": {    "計算機系": {},    "機器系": {},    "軟件系": {},   },   "登封理工大學": {    "數學系": {},    "化學系": {},    "物理系": {},   },  }, },}#exit_flag = Falsewhile True: for i in data :  print (i) choice = input ("input:") if choice in data:  while True:   for i2 in data[choice]:    print (i2)   choice2 = input("input2:")   if choice2 in data[choice]:    while True:     for i3 in data[choice][choice2]:      print (i3)     choice3 = input("input3:")     if choice3 in data[choice][choice2]:      for i4 in data[choice][choice2][choice3]:       print(i4)      choice4 = input("Press b to return to the previous level:")      if choice4 == "b":       pass      elif choice4 == "q":       exit ()     if choice3 == "b":      break     elif choice3 == "q":      exit()   if choice2 == "b":    break   elif choice2 == "q":    exit()