diff --git a/kakao_2021_blind/advertise_inserting.py b/kakao_2021_blind/advertise_inserting.py
new file mode 100644
index 0000000..6fe34ed
--- /dev/null
+++ b/kakao_2021_blind/advertise_inserting.py
@@ -0,0 +1,71 @@
+def chagne_time_to_sec(time):
+    h, m, s = map(int, time.split(":"))
+
+    return h * 3600 + m * 60 + s
+
+def change_sec_to_time(sec):
+    m, s = divmod(sec, 60)
+    h, m = divmod(m, 60)
+
+    h, m, s = map(str, [h,m,s])
+
+    h = h.zfill(2)
+    m = m.zfill(2)
+    s = s.zfill(2)
+
+    time = ":".join([h,m,s])
+    return  time
+
+
+
+def sum_watching_player(psum_of_time, logs):
+
+    for log in logs:
+        start_time, end_time = map(chagne_time_to_sec, log.split("-"))
+
+        psum_of_time[start_time] = psum_of_time[start_time] + 1
+        psum_of_time[end_time] = psum_of_time[end_time] -1
+
+
+    for i in range(1, len(psum_of_time)):
+        psum_of_time[i] = psum_of_time[i] + psum_of_time[i - 1]
+
+def solution(play_time, adv_time, logs):
+    answer = ''
+
+    play_time_sec = chagne_time_to_sec(play_time)
+    psum_of_time = [0] * (play_time_sec + 1)
+
+    adv_time_sec = chagne_time_to_sec(adv_time)
+
+    sum_watching_player(psum_of_time, logs)
+
+    max_watching_time = 0
+    watching_time = 0
+    start_time_sec = 0
+
+    for i in range(1, adv_time_sec):
+        max_watching_time += psum_of_time[i-1]
+
+    watching_time = max_watching_time
+        
+    for i in range(adv_time_sec, len(psum_of_time)):
+        watching_time = watching_time + psum_of_time[i - 1] - psum_of_time[i - adv_time_sec - 1]
+
+        if max_watching_time < watching_time:
+            max_watching_time = watching_time
+            start_time_sec = i - adv_time_sec
+
+    start_time = change_sec_to_time(start_time_sec)
+
+    return start_time
+
+
+
+
+if __name__ == "__main__":
+    play_time = "99:59:59"
+    adv_time = "25:00:00"
+    logs = ["69:59:59-89:59:59", "01:00:00-21:00:00", "79:59:59-99:59:59", "11:00:00-31:00:00"]
+
+    print(solution(play_time, adv_time, logs))
diff --git a/kakao_2021_blind/menu_renewal.py b/kakao_2021_blind/menu_renewal.py
new file mode 100644
index 0000000..57bc28e
--- /dev/null
+++ b/kakao_2021_blind/menu_renewal.py
@@ -0,0 +1,54 @@
+from collections import Counter
+from collections import defaultdict
+
+import itertools
+
+def solution(orders, course):
+    answer = []
+    cand_comb_menu = []
+
+    for num in course:
+        for order in orders:
+            comb_menues = list(itertools.combinations(order, num))
+
+            #AC, AD, AE
+            for comb_menu in comb_menues:
+                comb_menu = sorted(comb_menu)
+                cand_comb_menu.append("".join(comb_menu))
+
+    cand_comb_menu = Counter(cand_comb_menu).most_common()
+
+    best_like_dict = defaultdict(int)
+
+    for course_num in course:
+        best_like = 0
+
+        for menu, like in cand_comb_menu:
+            if len(menu) == course_num:
+                best_like = max(best_like, like)
+
+        best_like_dict[course_num] = best_like
+
+    
+    for course_num in course:
+        if best_like_dict[course_num] == 0 or best_like_dict[course_num] < 2:
+            continue
+
+        for menu, like in cand_comb_menu:
+            if len(menu) == course_num and like == best_like_dict[course_num]:
+                answer.append(menu)
+
+    print(sorted(answer))
+    return answer
+
+
+if __name__ == "__main__":
+    orders = ["ABCDE", "AB", "CD", "ADE", "XYZ", "XYZ", "ACD"]
+    course = [2,3,5]
+
+    solution(orders, course)
+    
+
+
+
+    
\ No newline at end of file
diff --git a/kakao_2021_blind/searching_ranking.py b/kakao_2021_blind/searching_ranking.py
new file mode 100644
index 0000000..64d9b6f
--- /dev/null
+++ b/kakao_2021_blind/searching_ranking.py
@@ -0,0 +1,59 @@
+import bisect
+from copy import deepcopy
+from itertools import combinations
+
+
+def make_sub_query(info):
+    keys = []
+    keys.append(" ".join(info))
+    for k in range(1, 5):
+        for sub in list(combinations(range(0, 4), k)):
+            case = deepcopy(info)
+
+            for idx in sub:
+                case[idx] = '-'
+
+            keys.append(" ".join(case))
+    return keys
+
+
+def solution(infos, querys):
+
+    info_dict = {}
+    
+    for info in infos:
+        lang, ground, pos, food, score = info.split()
+        query_set = make_sub_query([lang, ground, pos, food])
+
+        for q in query_set:
+            if q in info_dict.keys():
+                info_dict[q].append(int(score))
+            else:
+                info_dict[q] = [int(score)]
+
+    for key in info_dict.keys():
+        info_dict[key].sort()
+
+    answer = []
+
+    for q in querys:
+        q = q.replace(" and", "")
+        lang, ground, pos, food, score = q.split()
+
+        query_of_key = " ".join([lang, ground, pos, food])
+
+        if query_of_key in info_dict.keys():
+            score_list = info_dict[query_of_key]
+            answer.append(len(score_list) - bisect.bisect_left(score_list, int(score)))
+
+        else:
+            print("Asd")
+            answer.append(0)
+
+    return answer
+    
+
+if __name__ == "__main__":
+    info = ["java backend junior pizza 150","python frontend senior chicken 210","python frontend senior chicken 150","cpp backend senior pizza 260","java backend junior chicken 80","python backend senior chicken 50"]
+    query = ["java and backend and junior and pizza 100","python and frontend and senior and chicken 200","cpp and - and senior and pizza 250","- and backend and senior and - 150","- and - and - and chicken 100","- and - and - and - 150"]
+    print(solution(info, query))
\ No newline at end of file