diff --git a/froglike6/README.md b/froglike6/README.md
index bcaf431..90f5cd8 100644
--- a/froglike6/README.md
+++ b/froglike6/README.md
@@ -12,4 +12,5 @@
  | 8차시 | 2025.04.11 | 물리학 | [곰곰이와 시소](https://www.acmicpc.net/problem/26072)|https://github.com/AlgoLeadMe/AlgoLeadMe-13/pull/31|
  | 9차시 | 2025.04.30 | 기하학 | [평행사변형](https://www.acmicpc.net/problem/1064)|https://github.com/AlgoLeadMe/AlgoLeadMe-13/pull/34|
  | 10차시 | 2025.05.08 | 이분탐색 | [게임](https://www.acmicpc.net/problem/1072)|https://github.com/AlgoLeadMe/AlgoLeadMe-13/pull/42|
+ | 11차시 | 2025.05.08 | 조합론 | [High Towers](https://www.acmicpc.net/problem/33785)|https://github.com/AlgoLeadMe/AlgoLeadMe-13/pull/43|
  ---
diff --git a/froglike6/combinatorics/33785.py b/froglike6/combinatorics/33785.py
new file mode 100644
index 0000000..8173e29
--- /dev/null
+++ b/froglike6/combinatorics/33785.py
@@ -0,0 +1,4 @@
+import sys
+input=sys.stdin.readline
+n=int(input())
+print((n*(n+1)*(n+2))//6)
\ No newline at end of file