diff --git a/boj/class5/16566.py b/boj/class5/16566.py
new file mode 100644
index 0000000..caa662d
--- /dev/null
+++ b/boj/class5/16566.py
@@ -0,0 +1,35 @@
+# Ex_16566 카드게임 [플5]
+# upper bound
+def upperBound(target):
+    s, e = 0, M
+
+    while s < e:
+        mid = (s + e) // 2
+        if cards[mid] <= target:
+            s = mid + 1
+        else:
+            e = mid
+    return e
+
+
+def find(x):
+    if graph[x] != x:
+        graph[x] = find(graph[x])
+    return graph[x]
+
+
+def union(child, parent):
+    if parent < M:
+        graph[find(child)] = find(parent)
+
+
+N, M, K = map(int, input().split())
+cards = sorted(map(int, input().split()))
+cCards = list(map(int, input().split()))
+graph = list(i for i in range(M))
+
+for cCard in cCards:
+    index = find(upperBound(cCard))
+    print(cards[index])
+
+    union(index, index + 1)