diff --git a/9mean/20220327/1978.py b/9mean/20220327/1978.py
new file mode 100644
index 0000000..1339f18
--- /dev/null
+++ b/9mean/20220327/1978.py
@@ -0,0 +1,31 @@
+import sys
+global n
+
+
+def checkValid(x, position):
+    l = len(x)
+    for i in range(position, n):
+
+        if x == phoneList[i][:l]:
+            return 1
+    return 0
+
+
+t = int(input())
+for i in range(t):
+    n = int(input())
+    flag = 0
+    idx = 0
+    phoneList = []
+    for j in range(n):
+        num = input()
+        phoneList.append(num)
+    phoneList.sort()
+    for k in phoneList:
+        if checkValid(k, idx + 1) == 1:
+            flag = 1
+            print("NO")
+            break
+        idx += 1
+    if flag == 0:
+        print("YES")
\ No newline at end of file
diff --git a/9mean/privateSolved/1309.py b/9mean/privateSolved/1309.py
new file mode 100644
index 0000000..fedfa47
--- /dev/null
+++ b/9mean/privateSolved/1309.py
@@ -0,0 +1,9 @@
+n = int(input())
+s = [[0] * 3 for i in range(100001)]
+for i in range(3):
+    s[1][i] = 1
+for i in range(2, 100001):
+    s[i][0] = s[i - 1][1] + s[i - 1][2] % 9901
+    s[i][1] = s[i - 1][0] + s[i - 1][2] % 9901
+    s[i][2] = s[i - 1][0] + s[i - 1][1] + s[i - 1][2] % 9901
+print(sum(s[n]) % 9901)
\ No newline at end of file