diff --git "a/BOJ/1000-5000353円262円210円/JY_2170.java" "b/BOJ/1000-5000353円262円210円/JY_2170.java"
new file mode 100644
index 00000000..c6cc4d10
--- /dev/null
+++ "b/BOJ/1000-5000353円262円210円/JY_2170.java"
@@ -0,0 +1,66 @@
+import java.io.*;
+import java.util.*;
+public class JY_2170 {
+	
+	static class Pos implements Comparable<pos> {
+		int x, y;
+
+		public Pos(int x, int y) {
+			super();
+			this.x = x;
+			this.y = y;
+		}
+		@Override
+		public int compareTo(Pos other) {
+			return this.x - other.x;
+		}
+
+		@Override
+		public String toString() {
+			return "Pos [x=" + x + ", y=" + y + "]";
+		}
+		
+	}
+
+	public static void main(String[] args) throws IOException {
+		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+		StringTokenizer st = new StringTokenizer(br.readLine());
+		
+		int N = Integer.parseInt(st.nextToken());
+		
+		List<pos> pList = new ArrayList<strong>();
+		for(int i=0; i<n; i++) { + st = new StringTokenizer(br.readLine()); + int x = Integer.parseInt(st.nextToken()); + int y = Integer.parseInt(st.nextToken()); + + pList.add(new Pos(x, y)); + } + + // x기준으로 정렬 + Collections.sort(pList); + + int s = pList.get(0).x; + int e = pList.get(0).y; + int ans = 0; + for(int i=1; i<n; i++) { + Pos now = pList.get(i); + + // now.x가 end보다 작다면 겹침 -> end 갱신
+			if(e>= now.x) {
+				e = Math.max(e, now.y);
+			}
+			// 겹치지 않는 경우
+			else {
+				// 기존것 더해주고 새로 업데이트
+				ans += (e - s);
+				s = now.x;
+				e = now.y;
+			}
+		}
+		ans += (e - s);
+		System.out.println(ans);
+
+	}
+
+}
diff --git "a/BOJ/1000-5000353円262円210円/JY_2504.java" "b/BOJ/1000-5000353円262円210円/JY_2504.java"
new file mode 100644
index 00000000..7faad233
--- /dev/null
+++ "b/BOJ/1000-5000353円262円210円/JY_2504.java"
@@ -0,0 +1,51 @@
+import java.io.*;
+import java.util.*;
+public class JY_2504 {
+
+	public static void main(String[] args) throws IOException {
+		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+		
+		String line = br.readLine();
+		
+		Stack<character> stack = new Stack<strong>();
+		
+		int ans = 0;
+		int tmp = 1;
+		for(int i=0; i<line.length(); i++) {
+			char ch = line.charAt(i);
+			// 열린괄호
+			if(ch == '(') {
+				stack.push(ch);
+				tmp *= 2;
+			} else if(ch == '[') {
+				stack.push(ch);
+				tmp *= 3;
+			}
+			// 닫힌 괄호
+			else {
+				if(stack.isEmpty()) {
+					ans = 0;
+					break;
+				}
+				// 올바르지 않은 괄호
+				if((ch == ')' && stack.peek() == '[') &#124;&#124; (ch == ']' && stack.peek() =='(')) {
+					ans = 0;
+					break;
+				}
+				// 이전 값이 올바른 괄호라면 값 저장
+				if(ch == ')') {
+					if(line.charAt(i-1)=='(') ans += tmp;
+					tmp /= 2;
+				} else {
+					if(line.charAt(i-1)=='[') ans += tmp;
+					tmp /= 3;
+				}
+				stack.pop();
+			}
+		}
+		
+		if(!stack.isEmpty()) System.out.println(0);
+		else System.out.println(ans);
+	}
+
+}
diff --git "a/SQL/21354円243円274円354円260円250円/JY_FrontEnd_352円260円234円353円260円234円354円236円220円_354円260円276円352円270円260円.sql" "b/SQL/21354円243円274円354円260円250円/JY_FrontEnd_352円260円234円353円260円234円354円236円220円_354円260円276円352円270円260円.sql"
new file mode 100644
index 00000000..6c27dde4
--- /dev/null
+++ "b/SQL/21354円243円274円354円260円250円/JY_FrontEnd_352円260円234円353円260円234円354円236円220円_354円260円276円352円270円260円.sql"
@@ -0,0 +1,8 @@
+-- https://school.programmers.co.kr/learn/courses/30/lessons/276035
+-- FrontEnd 개발자 찾기
+SELECT DISTINCT A.ID, A.EMAIL, A.FIRST_NAME, A.LAST_NAME
+FROM DEVELOPERS A
+JOIN SKILLCODES B
+ON A.SKILL_CODE & B.CODE = B.CODE
+WHERE CATEGORY = "Front End"
+ORDER BY A.ID
\ No newline at end of file
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