diff --git a/README.md b/README.md
index 5d67ebd..97e7d13 100644
--- a/README.md
+++ b/README.md
@@ -41,5 +41,5 @@
 
 ![start.png](assets/start.png)
 
-测试通过会会给出接下来的迷题位置，也可以在 [目录测试类](src/test/kotlin/io/github/sor2171/puzzles/Catalog.kt) 中查看所有迷题。
+测试通过会给出接下来的迷题位置，也可以在 [目录测试类](src/test/kotlin/io/github/sor2171/puzzles/Catalog.kt) 中查看所有迷题。
 
diff --git a/src/main/kotlin/io/github/sor2171/puzzles/service/PuzzleNote.kt b/src/main/kotlin/io/github/sor2171/puzzles/service/PuzzleNote.kt
index 820f232..afec00c 100644
--- a/src/main/kotlin/io/github/sor2171/puzzles/service/PuzzleNote.kt
+++ b/src/main/kotlin/io/github/sor2171/puzzles/service/PuzzleNote.kt
@@ -7,17 +7,27 @@ class PuzzleNote(
     vararg notes: PuzzleNote? = arrayOf(null)
 ) {
     val className = CompileDetector.getColoredName(className)
-    val notes = notes.filterNotNull()
+    val notes = notes
 
     override fun toString(): String {
-        val validNotes = notes
-        if (validNotes.isEmpty()) return className
+        val sb = StringBuilder()
 
-        val builder = StringBuilder(className)
-        builder.append("\n    │")
-        for (note in validNotes) {
-            builder.append("\n    ├ ").append(note)
+        sb.append(className)
+
+        if (notes.size > 1) {
+            for (i in 1 until notes.size) {
+                sb.append("\n    │")
+                notes[i]?.let { note ->
+                    sb.append("\n    ├── ").append(note.className)
+                }
+            }
         }
-        return builder.toString()
+
+        val nextNote = notes.firstOrNull()
+        if (nextNote != null) {
+            sb.append("\n    │\n").append(nextNote.toString())
+        }
+
+        return sb.toString()
     }
 }
\ No newline at end of file
diff --git a/src/main/kotlin/io/github/sor2171/puzzles/utils/CatalogStructure.kt b/src/main/kotlin/io/github/sor2171/puzzles/utils/CatalogStructure.kt
index b107729..186c7d4 100644
--- a/src/main/kotlin/io/github/sor2171/puzzles/utils/CatalogStructure.kt
+++ b/src/main/kotlin/io/github/sor2171/puzzles/utils/CatalogStructure.kt
@@ -26,18 +26,22 @@ object CatalogStructure {
 
     val firstPuzzleNote: PuzzleNote
         get() {
-            var lastNote: PuzzleNote? = null
+            var nextMainNote: PuzzleNote? = null
+
             for (i in puzzlesArray.indices.reversed()) {
                 val array = puzzlesArray[i]
-                val noteArray = Array(array.size - 1) { i ->
-                    PuzzleNote(array[i + 1])
+
+                val children = Array(array.size) { index ->
+                    if (index == 0) {
+                        nextMainNote
+                    } else {
+                        PuzzleNote(array[index])
+                    }
                 }
-                lastNote = PuzzleNote(
-                    array[0],
-                    *noteArray
-                )
+
+                nextMainNote = PuzzleNote(array[0], *children)
             }
-            return lastNote!!
+            return nextMainNote!!
         }
 
     fun printAllMessage() = println(firstPuzzleNote)
diff --git a/src/test/kotlin/io/github/sor2171/puzzles/alphabet/You need a function, not a mathematical one.kt b/src/test/kotlin/io/github/sor2171/puzzles/alphabet/You need a function, not a mathematical one.kt
new file mode 100644
index 0000000..7009257
--- /dev/null
+++ b/src/test/kotlin/io/github/sor2171/puzzles/alphabet/You need a function, not a mathematical one.kt	
@@ -0,0 +1,26 @@
+@file:SkipCompile(skip = true)
+@file:Suppress("ClassName")
+
+package io.github.sor2171.puzzles.alphabet
+
+import io.github.sor2171.puzzles.annotation.SkipCompile
+import org.junit.jupiter.api.Test
+
+/**
+ * 你需要写一个函数，目标是把一个 [Pair] 的两个值相交换
+ */
+class `You need a function, not a mathematical one` {
+
+    // write start 1
+    fun
+    // write  end  1
+
+    @Test
+    fun puzzle() {
+        val pair = "abc" to 123
+        val new = exchange(pair)
+        println(pair)
+        println(new)
+        assert(new.first == pair.second && new.second == pair.first)
+    }
+}
\ No newline at end of file