diff --git a/ParkHyunS00/16472.java b/ParkHyunS00/16472.java
new file mode 100644
index 0000000..9ec4cef
--- /dev/null
+++ b/ParkHyunS00/16472.java
@@ -0,0 +1,37 @@
+import java.util.*;
+import java.io.*;
+
+public class Main {
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        int N = Integer.parseInt(br.readLine());
+        String catSpeak = br.readLine();
+        int[] alphabetFrequency = new int[26];
+
+        int index = 0;
+        int length = 1;
+        for (int i=0; i<catSpeak.length(); i++) {
+            while (index < catSpeak.length()) {
+                alphabetFrequency[catSpeak.charAt(index++) - 'a']++;
+
+                if (getAlphabetCount(alphabetFrequency) > N) {
+                    alphabetFrequency[catSpeak.charAt(--index) - 'a']--;
+                    break;
+                }
+            }
+
+            length = Math.max(length, index - i);
+            alphabetFrequency[catSpeak.charAt(i) - 'a']--;
+        }
+        System.out.print(length);
+    }
+
+    static int getAlphabetCount(int[] alphabetFrequency) {
+        int count = 0;
+
+        for (int i=0; i<alphabetFrequency.length; i++) {
+            if (alphabetFrequency[i] > 0) count++;
+        }
+        return count;
+    }
+}
diff --git a/ParkHyunS00/1806.java b/ParkHyunS00/1806.java
new file mode 100644
index 0000000..0bbbca6
--- /dev/null
+++ b/ParkHyunS00/1806.java
@@ -0,0 +1,32 @@
+import java.util.*;
+import java.io.*;
+
+public class Main {
+    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());
+        int S = Integer.parseInt(st.nextToken());
+        int[] arr = new int[N];
+
+        st = new StringTokenizer(br.readLine());
+        for (int i=0; i<N; i++) {
+            arr[i] = Integer.parseInt(st.nextToken());
+        }
+
+        int length = 100_001;
+        int index = 0;
+        int currSum = arr[0];
+        for (int i=0; i<N; i++) {
+            while (currSum < S && index < N - 1) currSum += arr[++index];
+
+            if (currSum >= S) {
+                length = Math.min(index - i + 1, length);
+            }
+
+            currSum -= arr[i];
+        }
+
+        System.out.print((length == 100_001) ? 0 : length);
+    }
+}
diff --git a/ParkHyunS00/2531.java b/ParkHyunS00/2531.java
new file mode 100644
index 0000000..36b8b13
--- /dev/null
+++ b/ParkHyunS00/2531.java
@@ -0,0 +1,35 @@
+import java.util.*;
+import java.io.*;
+
+public class Main {
+    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());
+        int d = Integer.parseInt(st.nextToken());
+        int k = Integer.parseInt(st.nextToken());
+        int c = Integer.parseInt(st.nextToken());
+        int[] sushiKinds = new int[d + 1];
+        int[] dishes = new int[N];
+
+        for (int i=0; i<N; i++) {
+            dishes[i] = Integer.parseInt(br.readLine());
+        }
+
+        int unique = 0;
+        for (int i=0; i<k-1; i++) {
+            if (sushiKinds[dishes[i]]++ == 0) unique++;
+        }
+
+        int result = 0;
+        for (int i=0; i<N; i++) {
+            if (sushiKinds[dishes[(i + k - 1) % N]]++ == 0) unique++;
+
+            result = Math.max(result, unique + (sushiKinds[c] == 0 ? 1 : 0));
+            sushiKinds[dishes[i]]--;
+            if (sushiKinds[dishes[i]] == 0) unique--;
+        }
+
+        System.out.print(result);
+    }
+}