diff --git "a/lkhyun/202503/23 BOJ G1 \354\235\214\354\243\274\354\275\224\353\224\251.md" "b/lkhyun/202503/23 BOJ G1 \354\235\214\354\243\274\354\275\224\353\224\251.md"
new file mode 100644
index 00000000..ebc4daf6
--- /dev/null
+++ "b/lkhyun/202503/23 BOJ G1 \354\235\214\354\243\274\354\275\224\353\224\251.md"	
@@ -0,0 +1,84 @@
+```java
+import java.util.*;
+import java.io.*;
+public class Main {
+    static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+    static BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
+    static StringTokenizer st;
+    static int N = 0;
+    static int K = 0;
+    static int[] arr;
+    static int[] tree;
+    public static void main(String[] args) throws Exception {
+        st = new StringTokenizer(br.readLine());
+        while(st.hasMoreTokens()){
+            N = Integer.parseInt(st.nextToken());
+            K = Integer.parseInt(st.nextToken());
+            arr = new int[N+1];
+            tree = new int[4*N];
+
+            st = new StringTokenizer(br.readLine());
+            for(int i=1;i<=N;i++){
+                arr[i] = Integer.parseInt(st.nextToken());
+            }
+            init(1,1,N);
+            for(int i=1;i<=K;i++){
+                st = new StringTokenizer(br.readLine());
+                String cmd = st.nextToken();
+                if(cmd.equals("C")){//변경
+                    int idx = Integer.parseInt(st.nextToken());
+                    int newValue = Integer.parseInt(st.nextToken());
+
+                    if(newValue>0) update(1,1,N,idx,1);
+                    else if(newValue<0) update(1,1,N,idx,-1);
+                    else update(1,1,N,idx,0);
+
+                }else if(cmd.equals("P")){//곱셈
+                    int left = Integer.parseInt(st.nextToken());
+                    int right = Integer.parseInt(st.nextToken());
+                    int result = multiplication(1,1,N,left,right);
+                    if(result>0) bw.write("+");
+                    else if(result<0) bw.write("-");
+                    else bw.write("0");
+                }
+            }
+            bw.write("\n");
+
+            String nextcmd = br.readLine();
+            if(nextcmd == null) break;
+            else st = new StringTokenizer(nextcmd);
+        }
+        bw.close();
+    }
+    public static void init(int cur, int start, int end){
+        if(start==end){
+            if(arr[start]>0) tree[cur] = 1;
+            else if(arr[start]<0) tree[cur] = -1;
+            else tree[cur] = 0;
+        }else{
+            init(cur*2,start,(start+end)/2);
+            init(cur*2 + 1, (start+end)/2 + 1,end);
+            tree[cur] = tree[cur*2] * tree[cur*2 + 1];
+        }
+    }
+    public static void update(int cur, int start, int end, int idx, int newValue){
+        if(idx<start || idx>end) return;
+        if(start == end) {
+            tree[cur] = newValue;
+            return;
+        }
+        update(cur * 2, start, (start + end) / 2, idx, newValue);
+        update(cur * 2 + 1, (start + end) / 2 + 1, end, idx, newValue);
+        tree[cur] = tree[cur*2] * tree[cur*2 + 1];
+    }
+    public static int multiplication(int cur, int start, int end, int left, int right){
+        if(right<start || left>end) return 1;
+        if(left<=start && right>=end) return tree[cur];
+
+        int l = multiplication(cur*2,start,(start+end)/2,left,right);
+        int r = multiplication(cur*2 + 1, (start+end)/2 + 1,end,left,right);
+        return l*r;
+    }
+}
+
+```