diff --git "a/khj20006/202509/21 BOJ G4 \354\235\200\355\225\230\354\262\240\353\217\204.md" "b/khj20006/202509/21 BOJ G4 \354\235\200\355\225\230\354\262\240\353\217\204.md"
new file mode 100644
index 00000000..2139a19c
--- /dev/null
+++ "b/khj20006/202509/21 BOJ G4 \354\235\200\355\225\230\354\262\240\353\217\204.md"	
@@ -0,0 +1,91 @@
+```java
+import java.io.*;
+import java.util.*;
+
+class IOController {
+	BufferedReader br;
+	BufferedWriter bw;
+	StringTokenizer st;
+
+	public IOController() {
+		br = new BufferedReader(new InputStreamReader(System.in));
+		bw = new BufferedWriter(new OutputStreamWriter(System.out));
+		st = new StringTokenizer("");
+	}
+
+	String nextLine() throws Exception {
+		String line = br.readLine();
+		st = new StringTokenizer(line);
+		return line;
+	}
+
+	String nextToken() throws Exception {
+		while (!st.hasMoreTokens())
+			nextLine();
+		return st.nextToken();
+	}
+
+	int nextInt() throws Exception {
+		return Integer.parseInt(nextToken());
+	}
+
+	long nextLong() throws Exception {
+		return Long.parseLong(nextToken());
+	}
+
+	double nextDouble() throws Exception {
+		return Double.parseDouble(nextToken());
+	}
+
+	void close() throws Exception {
+		bw.flush();
+		bw.close();
+	}
+
+	void write(String content) throws Exception {
+		bw.write(content);
+	}
+
+}
+
+public class Main {
+
+	static IOController io;
+
+	//
+
+	static int N, M;
+	static long[] c;
+	static int[] r;
+
+	static int f(int x) {return x==r[x] ? x : (r[x]=f(r[x]));}
+
+	public static void main(String[] args) throws Exception {
+
+		io = new IOController();
+
+		N = io.nextInt();
+		M = io.nextInt();
+		r = new int[N+1];
+		c = new long[N+1];
+		for(int i=1;i<=N;i++) {
+			c[i] = io.nextLong();
+			r[i] = i;
+		}
+
+		while(M-->0) {
+			int x = f(io.nextInt());
+			int y = f(io.nextInt());
+			if(x != y) {
+				c[y] += c[x];
+				r[x] = y;
+			}
+			io.write(c[y] + "\n");
+		}
+
+		io.close();
+
+	}
+
+}
+```