diff --git a/0510/BOJ/P1764/P1764_yu.java b/0510/BOJ/P1764/P1764_yu.java
new file mode 100644
index 0000000..c5a050f
--- /dev/null
+++ b/0510/BOJ/P1764/P1764_yu.java
@@ -0,0 +1,45 @@
+
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.HashMap;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Scanner;
+
+public class bj_1764_듣보잡 {
+public static void main(String[] args) {
+	
+	Scanner sc = new Scanner(System.in);
+	
+	StringBuilder sb = new StringBuilder();
+	
+	int n = sc.nextInt(); // 못들어본 사람
+	int m = sc.nextInt(); // 못본사람
+	
+	HashMap<String, String> nosee = new HashMap<>();
+	
+	for(int i=0; i<n; i++) {
+		nosee.put(sc.next(), "no");
+	}
+	
+	int cnt = 0;
+	
+	List<String> pick = new LinkedList<>();
+	
+	for(int i=0; i<m; i++) {
+		String word = sc.next();
+		if(nosee.get(word)!=null) {
+			cnt++;
+			pick.add(word);
+		}
+	}
+	
+	Collections.sort(pick);
+	
+	System.out.println(cnt);
+	for(int i=0; i<cnt; i++) {
+		System.out.println(pick.get(i));
+	}
+}
+}
diff --git a/0510/BOJ/P1780/P1780_yu.java b/0510/BOJ/P1780/P1780_yu.java
new file mode 100644
index 0000000..daff5b9
--- /dev/null
+++ b/0510/BOJ/P1780/P1780_yu.java
@@ -0,0 +1,58 @@
+import java.util.Scanner;
+
+public class bj_1780_종이의개수 {
+
+	static int n;
+	static int[][] paper;
+	static int[] cnt;
+
+	public static void main(String[] args) {
+
+		Scanner sc = new Scanner(System.in);
+
+		n = sc.nextInt(); // N
+
+		paper = new int[n][n];
+
+		cnt = new int[3];
+
+		for (int i = 0; i < n; i++) {
+			for (int j = 0; j < n; j++) {
+				paper[i][j] = sc.nextInt();
+			}
+		} // 입력받기
+		
+		divide(0, 0, n); // 분할정복!!!
+		
+		for(int i=0; i<3; i++) {
+			System.out.println(cnt[i]);
+		}
+
+	}
+
+	public static boolean pcheck(int row, int col, int len) {
+		int num = paper[row][col];
+		for (int i = row; i < row + len; i++) {
+			for (int j = col; j < col + len; j++) {
+				if (paper[i][j] != num) {
+					return false;
+				}
+			}
+		}
+		return true;
+	}
+	
+	 public static void divide(int row, int col, int len) {  
+	        if(pcheck(row, col, len)) {
+	            int num = paper[row][col];
+	            cnt[num + 1] ++; //-1때문에 "값+1 == 인덱스"
+	        }else {
+	            int nextLen = len / 3;
+	            for(int i = 0; i < 3; i++) {
+	                for(int j = 0; j < 3; j++) {
+	                	divide(row + i*nextLen, col + j*nextLen, nextLen);
+	                }
+	            }
+	        }
+	    }
+}
diff --git a/0510/BOJ/P1927/P1927_yu.java b/0510/BOJ/P1927/P1927_yu.java
new file mode 100644
index 0000000..a639814
--- /dev/null
+++ b/0510/BOJ/P1927/P1927_yu.java
@@ -0,0 +1,33 @@
+import java.util.PriorityQueue;
+import java.util.Scanner;
+
+public class bj_1927_최소힙 {
+public static void main(String[] args) {
+	
+	Scanner sc = new Scanner(System.in);
+	
+	PriorityQueue<Integer> pq = new PriorityQueue<>();
+	
+	int n = sc.nextInt();
+	
+	StringBuilder sb = new StringBuilder();
+	
+	for(int i = 0; i<n; i++) {
+		
+		int num = sc.nextInt();
+		
+		if(num == 0) {
+			if(pq.isEmpty()) {
+				sb.append(0).append("\n");
+			}else {
+				sb.append(pq.poll()).append("\n");
+			}
+		}else {
+			pq.add(num);
+			//System.out.println(sb.toString());
+		}
+	}
+	
+	System.out.println(sb);
+}
+}
diff --git "a/0510/Programmers/Lv1/\354\227\206\353\212\224\354\210\253\354\236\220\353\215\224\355\225\230\352\270\260_yu.java" "b/0510/Programmers/Lv1/\354\227\206\353\212\224\354\210\253\354\236\220\353\215\224\355\225\230\352\270\260_yu.java"
new file mode 100644
index 0000000..dc057bc
--- /dev/null
+++ "b/0510/Programmers/Lv1/\354\227\206\353\212\224\354\210\253\354\236\220\353\215\224\355\225\230\352\270\260_yu.java"
@@ -0,0 +1,26 @@
+
+public class lv1_없는숫자더하기 {
+	public static void main(String[] args) {
+		
+		int[] numbers = {1,2,3,4,6,7,8,0};
+		
+		//
+		
+		int answer = 0;
+		
+		for(int i=0; i<=9; i++) {
+			boolean flag = false;
+			for(int j=0; j<numbers.length; j++) {
+				if(numbers[j] == i) {
+					flag = true;
+				}
+			}
+			if(!flag) {
+				answer+=i;
+			}
+		}
+		
+		System.out.println(answer);
+	}
+
+}
diff --git "a/0510/Programmers/Lv2/\354\225\225\354\266\225_yu.java" "b/0510/Programmers/Lv2/\354\225\225\354\266\225_yu.java"
new file mode 100644
index 0000000..b798b11
--- /dev/null
+++ "b/0510/Programmers/Lv2/\354\225\225\354\266\225_yu.java"
@@ -0,0 +1,48 @@
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+public class lv2_압축 {
+	public static void main(String[] args) {
+
+		String msg = "KAKAO";
+
+		//
+
+		ArrayList<String> alp = new ArrayList<>(Arrays.asList("1", "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R",
+				"S", "T", "U", "V", "W", "X", "Y", "Z"));
+		
+		List<Integer> ans = new ArrayList<>();
+		
+		outer: for(int i=0; i<msg.length(); i++) {
+			int idx = i+2;
+			while(idx<=msg.length()) {
+				if(alp.contains(msg.substring(i, idx))) {
+					idx++;
+				}else {
+					alp.add(msg.substring(i, idx));
+					//System.out.println(msg.substring(i, idx));
+					ans.add(alp.indexOf(msg.substring(i, idx-1)));
+					//System.out.println(msg.substring(i, idx-1));
+					i = idx-2;
+					//System.out.println(i);
+					break;
+				}
+			}
+			// 마지막부분 처리
+			if(idx>msg.length()) {
+				ans.add(alp.indexOf(msg.substring(i, msg.length())));
+				break outer;
+			}
+		}
+		
+		// 정답 배열로 출력
+		int[] answer = new int[ans.size()];
+		
+		for(int i=0; i<ans.size(); i++) {
+			answer[i] = ans.get(i);
+		}
+		
+		System.out.println(Arrays.toString(answer));
+	}
+}
diff --git "a/0512/Programmers/Lv1/\354\235\214\354\226\221\353\215\224\355\225\230\352\270\260_yu.java" "b/0512/Programmers/Lv1/\354\235\214\354\226\221\353\215\224\355\225\230\352\270\260_yu.java"
new file mode 100644
index 0000000..f583e93
--- /dev/null
+++ "b/0512/Programmers/Lv1/\354\235\214\354\226\221\353\215\224\355\225\230\352\270\260_yu.java"
@@ -0,0 +1,22 @@
+
+public class lv1_음양더하기 {
+	public static void main(String[] args) {
+		
+		int[] absolutes = {4, 7, 12};
+		boolean[] signs = {true,false,true}; // true: 양수 false: 음수
+		int answer = 0;
+		
+		//
+		
+		for(int i=0; i<signs.length; i++) {
+			if(signs[i]) {
+				answer+= absolutes[i];
+			}else {
+				answer-= absolutes[i];
+			}
+		}
+		
+		System.out.println(answer);
+	}
+
+}