diff --git a/CMakeLists.txt b/CMakeLists.txt
index f3400d6..ebc1fac 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -6,7 +6,7 @@ add_compile_options(-fsanitize=address,pointer-compare,pointer-subtract,undefine
 add_link_options(-fsanitize=address,pointer-compare,pointer-subtract,undefined -fno-omit-frame-pointer)
 include_directories(${CMAKE_CURRENT_LIST_DIR}/include)
 
-set(CMAKE_CXX_STANDARD 20)
+set(CMAKE_CXX_STANDARD 26)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 set(CMAKE_CXX_EXTENSIONS OFF)
 
diff --git a/src/8/22/P4551.cpp b/src/8/22/P4551.cpp
new file mode 100644
index 0000000..7d49728
--- /dev/null
+++ b/src/8/22/P4551.cpp
@@ -0,0 +1,96 @@
+#include <algorithm>
+#include <iostream>
+#include <vector>
+
+void fast_io() {
+    std::ios_base::sync_with_stdio(false);
+    std::cin.tie(NULL);
+}
+
+const int MAXN = 100005;
+const int BITS = 31;
+std::vector<std::pair<int, int>> adj[MAXN];
+int dist[MAXN];
+namespace Trie {
+    int trie[MAXN * BITS][2];
+    int nodec;
+
+    void init() {
+        trie[0][0] = trie[0][1] = 0;
+        nodec = 1;
+    }
+
+    void insert(int val) {
+        int curnode = 0;
+
+        for (int i = BITS - 1; i >= 0; --i) {
+            int bit = (val >> i) & 1;
+            if (!trie[curnode][bit]) {
+
+                trie[nodec][0] = trie[nodec][1] = 0;
+                trie[curnode][bit] = nodec++;
+            }
+            curnode = trie[curnode][bit];
+        }
+    }
+
+    int query_max_xor(int val) {
+        int curnode = 0;
+        int maxorval = 0;
+        for (int i = BITS - 1; i >= 0; --i) {
+            int bit = (val >> i) & 1;
+
+            if (trie[curnode][!bit]) {
+                maxorval |= (1 << i);
+                curnode = trie[curnode][!bit];
+            } else {
+
+                curnode = trie[curnode][bit];
+            }
+        }
+        return maxorval;
+    }
+}
+
+void dfs(int u, int p, int curxorsum) {
+    dist[u] = curxorsum;
+    for (auto &edge : adj[u]) {
+        int v = edge.first;
+        int weight = edge.second;
+        if (v == p) {
+            continue;
+        }
+        dfs(v, u, curxorsum ^ weight);
+    }
+}
+
+int main() {
+    fast_io();
+
+    int n;
+    std::cin >> n;
+
+    for (int i = 0; i < n - 1; ++i) {
+        int u, v, w;
+        std::cin >> u >> v >> w;
+
+        adj[u].push_back({v, w});
+        adj[v].push_back({u, w});
+    }
+
+    dfs(1, 0, 0);
+
+    Trie::init();
+    for (int i = 1; i <= n; ++i) {
+        Trie::insert(dist[i]);
+    }
+
+    int max_ans = 0;
+    for (int i = 1; i <= n; ++i) {
+        max_ans = std::max(max_ans, Trie::query_max_xor(dist[i]));
+    }
+
+    std::cout << max_ans << '\n';
+
+    return 0;
+}
diff --git a/src/test.cpp b/src/test.cpp
index c7d4a71..312f870 100644
--- a/src/test.cpp
+++ b/src/test.cpp
@@ -1,64 +1,4 @@
-#include <list>
-class MyLinkedList {
-public:
-    std::list<int> l;
-    MyLinkedList() {
-        
-    }
-    
-    int get(int index) {
-        if(index>=l.size()){
-            return -1;
-        }
-        auto p = l.begin();
-        while(index--){
-            p++;
-        }
-        return *p;
-    }
-    
-    void addAtHead(int val) {
-        l.push_front(val);
-    }
-    
-    void addAtTail(int val) {
-        l.push_back(val);
-    }
-    
-    void addAtIndex(int index, int val) {
-        if(index==l.size()){
-            l.push_back(val);
-            return;
-        }
-        if(index>l.size())return;
-        auto p = l.begin();
-        while(index--){
-            ++p;
-        }
-        l.insert(p,val);
-    }   
-    
-    void deleteAtIndex(int index) {
-        if(0<=index && index<l.size()){
-            auto p = l.begin();
-            while(index--){
-                ++p;
-            }
-            l.erase(p);
-        }
-    }
-};
 
-/**
- * Your MyLinkedList object will be instantiated and called as such:
- * MyLinkedList* obj = new MyLinkedList();
- * int param_1 = obj->get(index);
- * obj->addAtHead(val);
- * obj->addAtTail(val);
- * obj->addAtIndex(index,val);
- * obj->deleteAtIndex(index);
- */
-
- int main(){
+int main(){
     
- }
\ No newline at end of file
+}
\ No newline at end of file