diff --git a/Seryeong/Baekjoon/DP/17626.py b/Seryeong/Baekjoon/DP/17626.py
new file mode 100644
index 0000000..89cea93
--- /dev/null
+++ b/Seryeong/Baekjoon/DP/17626.py
@@ -0,0 +1,24 @@
+# 17626 Four Squares
+import sys
+
+num = int(sys.stdin.readline())
+DP = [0] * (num + 1)
+
+i = 1
+while i**2 <= num:
+    DP[i**2] = 1  # 제곱수는 개수가 1개
+    i += 1
+
+for i in range(1, num + 1):
+    if DP[i] != 0:  # 제곱수이면 패스(어차피 최소이기 때문에)
+        continue
+
+    j = 1
+    while j*j <= i:  # 아직 개수를 안 셌을 때
+        if DP[i] == 0:
+            DP[i] = DP[i - j*j] + DP[j*j]  # 제곱수 개수 합치기
+        else:
+            DP[i] = min(DP[i], DP[i - j*j] + DP[j*j])  # 최소인 제곱수 개수로 업데이트
+        j += 1
+
+print(DP[-1])
diff --git a/Seryeong/Baekjoon/Greedy/16953.py b/Seryeong/Baekjoon/Greedy/16953.py
new file mode 100644
index 0000000..22ff6da
--- /dev/null
+++ b/Seryeong/Baekjoon/Greedy/16953.py
@@ -0,0 +1,21 @@
+# 16953 A -> B
+import sys
+
+A, B = map(int, sys.stdin.readline().split())
+
+cnt = 1
+while B != A:
+    if B % 2 == 0:  # 2로 나누어질 때
+        B = B // 2
+    elif B % 10 == 1:  # 뒷자리가 1로 끝날 때
+        B = B // 10
+    else:  # 아무 연산도 안될 경우
+        cnt = -1
+        break
+    cnt += 1
+
+    if B == 0:  # A를 B로 만들 수 없을 때
+        cnt = -1
+        break
+
+print(cnt)
diff --git a/Seryeong/Baekjoon/Implement/15787.py b/Seryeong/Baekjoon/Implement/15787.py
new file mode 100644
index 0000000..9646eb1
--- /dev/null
+++ b/Seryeong/Baekjoon/Implement/15787.py
@@ -0,0 +1,21 @@
+# 15787 기차가 어둠을 헤치고 은하수를
+import sys
+
+N, M = map(int, sys.stdin.readline().split())
+
+seats = [[0] * 20 for _ in range(N)]
+print(seats)
+for _ in range(M):
+    command = sys.stdin.readline().split()
+    type = int(command[0])
+    if type == 1:
+        if seats[command[1]][command[2]]:
+            seats[command[1]][command[2]] = 1
+    elif type == 2:
+        if not seats[command[1]][command[2]]:
+            seats[command[1]][command[2]] = 0
+    elif type == 3:
+        for i in range(20, -1):
+            seats[command[1]][i+1] = seats[command[1]][i]
+
+print(seats)
diff --git "a/Seryeong/Programmers/Lv1/K\353\262\210\354\247\270\354\210\230.py" "b/Seryeong/Programmers/Lv1/K\353\262\210\354\247\270\354\210\230.py"
new file mode 100644
index 0000000..eac456d
--- /dev/null
+++ "b/Seryeong/Programmers/Lv1/K\353\262\210\354\247\270\354\210\230.py"
@@ -0,0 +1,8 @@
+def solution(array, commands):
+    answer = []
+    for command in commands:
+        temp = array
+        temp = temp[command[0]-1:command[1]]
+        temp.sort()
+        answer.append(temp[command[2]-1])
+    return answer
diff --git "a/Seryeong/Programmers/Lv2/\353\215\224\353\247\265\352\262\214.py" "b/Seryeong/Programmers/Lv2/\353\215\224\353\247\265\352\262\214.py"
new file mode 100644
index 0000000..fcb7178
--- /dev/null
+++ "b/Seryeong/Programmers/Lv2/\353\215\224\353\247\265\352\262\214.py"
@@ -0,0 +1,19 @@
+# 정확성: 74.2
+# 효율성: 16.1
+# 합계: 90.3 / 100.0
+# import heapq
+# def solution(scoville, K):
+#     answer = 0
+#     heapq.heapify(scoville)
+#     while len(scoville) > 1:
+#         min1 = heapq.heappop(scoville)
+#         if min1 >= K:
+#             break
+#         min2 = heapq.heappop(scoville)
+
+#         scoville.append(min1 + min2 * 2)
+#         answer += 1
+
+#     if scoville[0] < K:
+#         return -1
+#     return answer