diff --git a/Two-Sum Problem/Solution 1/2Sum.playground/Contents.swift b/Two-Sum Problem/Solution 1/2Sum.playground/Contents.swift
index 00ce05136..4de46128c 100644
--- a/Two-Sum Problem/Solution 1/2Sum.playground/Contents.swift	
+++ b/Two-Sum Problem/Solution 1/2Sum.playground/Contents.swift	
@@ -1,4 +1,8 @@
 //: Playground - noun: a place where people can play
+// Last checked with: Version 9.0 beta 4 (9M189t)
+#if swift(>=4.0)
+print("Hello, Swift 4!")
+#endif
 
 func twoSumProblem(_ a: [Int], k: Int) -> ((Int, Int))? {
   var map = [Int: Int]()
diff --git a/Two-Sum Problem/Solution 2/2Sum.playground/Contents.swift b/Two-Sum Problem/Solution 2/2Sum.playground/Contents.swift
index 9a555f0eb..4cb3d9283 100644
--- a/Two-Sum Problem/Solution 2/2Sum.playground/Contents.swift	
+++ b/Two-Sum Problem/Solution 2/2Sum.playground/Contents.swift	
@@ -1,4 +1,8 @@
 //: Playground - noun: a place where people can play
+// Last checked with: Version 9.0 beta 4 (9M189t)
+#if swift(>=4.0)
+print("Hello, Swift 4!")
+#endif
 
 func twoSumProblem(_ a: [Int], k: Int) -> ((Int, Int))? {
   var i = 0
diff --git a/Two-Sum Problem/Solution 2/2Sum.playground/timeline.xctimeline b/Two-Sum Problem/Solution 2/2Sum.playground/timeline.xctimeline
deleted file mode 100644
index bf468afec..000000000
--- a/Two-Sum Problem/Solution 2/2Sum.playground/timeline.xctimeline	
+++ /dev/null
@@ -1,6 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<Timeline
-   version = "3.0">
-   <TimelineItems>
-   </TimelineItems>
-</Timeline>