diff --git "a/khj20006/202502/21 BOJ P3 \354\240\204\354\237\201 \354\244\221\354\235\230 \354\202\266.md" "b/khj20006/202502/21 BOJ P3 \354\240\204\354\237\201 \354\244\221\354\235\230 \354\202\266.md"
new file mode 100644
index 00000000..b2eaf5fd
--- /dev/null
+++ "b/khj20006/202502/21 BOJ P3 \354\240\204\354\237\201 \354\244\221\354\235\230 \354\202\266.md"	
@@ -0,0 +1,105 @@
+```java
+
+import java.util.*;
+import java.io.*;
+
+class Node{
+	int cnt;
+	Node l, r;
+	Node(){ cnt = 0; }
+}
+
+class Trie{
+	Node root;
+	Trie(){ root = new Node(); }
+	
+	void insert(long x) {
+		
+		Stack<Integer> S = new Stack<>();
+		while(x > 0) {
+			if((x&1) == 0) S.add(0);
+			else S.add(1);
+			x >>= 1;
+		}
+		
+		Node now = root;
+		while(!S.isEmpty()) {
+			int a = S.pop();
+			if(a == 0) {
+				if(now.l == null) now.l = new Node();
+				now = now.l;
+				now.cnt++;
+			}
+			else {
+				if(now.r == null) now.r = new Node();
+				now = now.r;
+				now.cnt++;
+			}
+		}
+	}
+	
+	int DFS(int v) {
+		Node now = root;
+		int ans = 1;
+		if(now.l != null) ans += dfs(now.l, v);
+		if(now.r != null) ans += dfs(now.r, v);
+		return ans;
+	}
+	
+	int dfs(Node now, int v) {
+		int res = now.cnt == v ? 0 : 1;
+		if(now.l != null) res += dfs(now.l, v);
+		if(now.r != null) res += dfs(now.r, v);
+		return res;
+	}
+}
+
+class Main {
+	
+	// IO field
+	static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+	static BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
+	static StringTokenizer st;
+
+	static void nextLine() throws Exception {st = new StringTokenizer(br.readLine());}
+	static int nextInt() {return Integer.parseInt(st.nextToken());}
+	static long nextLong() {return Long.parseLong(st.nextToken());}
+	static void bwEnd() throws Exception {bw.flush();bw.close();}
+	
+	// Additional field
+	
+	static Trie trie;
+	static int N;
+	
+	
+	public static void main(String[] args) throws Exception {
+		
+		ready();
+		solve();
+	
+		bwEnd();
+		
+	}
+	
+	static void ready() throws Exception{
+		
+		trie = new Trie();
+		
+		N = Integer.parseInt(br.readLine());
+		nextLine();
+		for(int i=0;i<N;i++) {
+			long a = nextLong();
+			trie.insert(a);
+		}		
+		
+	}
+	
+	static void solve() throws Exception{
+
+		bw.write(trie.DFS(N)+"\n");
+		
+	}
+	
+}
+
+```