diff --git "a/Ukj0ng/202508/21 BOJ G3 \354\210\230\354\203\201\355\203\235\354\213\234\354\213\234.md" "b/Ukj0ng/202508/21 BOJ G3 \354\210\230\354\203\201\355\203\235\354\213\234\354\213\234.md"
new file mode 100644
index 00000000..a3c8576f
--- /dev/null
+++ "b/Ukj0ng/202508/21 BOJ G3 \354\210\230\354\203\201\355\203\235\354\213\234\354\213\234.md"	
@@ -0,0 +1,67 @@
+```
+import java.io.*;
+import java.util.*;
+
+public class Main {
+    private static final BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+    private static final BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
+    private static List<int[]> reverse;
+    private static int N, M;
+    public static void main(String[] args) throws IOException {
+        init();
+        if (reverse.isEmpty()) {
+            bw.write(M + "\n");
+        } else {
+            reverse.sort((o1, o2) -> {
+                if (o1[0] == o2[0]) return Integer.compare(o1[1], o2[1]);
+                return Integer.compare(o1[0], o2[0]);
+            });
+
+            List<int[]> list = new ArrayList<>();
+            int[] current = reverse.get(0);
+
+            for (int i = 1; i < reverse.size(); i++) {
+                int[] next = reverse.get(i);
+                if (current[1] >= next[0]) {
+                    current[1] = Math.max(current[1], next[1]);
+                } else {
+                    list.add(new int[]{current[0], current[1]});
+                    current = next;
+                }
+            }
+
+            list.add(current);
+
+            long temp = M;
+
+            for (int[] element : list) {
+                temp += (element[1] - element[0]) * 2L;
+            }
+
+            bw.write(temp + "\n");
+        }
+        bw.flush();
+        bw.close();
+        br.close();
+    }
+
+    private static void init() throws IOException {
+        StringTokenizer st = new StringTokenizer(br.readLine());
+        N = Integer.parseInt(st.nextToken());
+        M = Integer.parseInt(st.nextToken());
+
+        reverse = new ArrayList<>();
+
+        for (int i = 0; i < N; i++) {
+            st = new StringTokenizer(br.readLine());
+            int x = Integer.parseInt(st.nextToken());
+            int y = Integer.parseInt(st.nextToken());
+
+            if (x > y) {
+                reverse.add(new int[]{y, x});
+            }
+        }
+    }
+}
+
+```