diff --git a/README.playground/Contents.swift b/README.playground/Contents.swift
new file mode 100644
index 0000000..630dff5
--- /dev/null
+++ b/README.playground/Contents.swift
@@ -0,0 +1,94 @@
+import UIKit
+
+//Create a function that receives an integers array and returns the number that appeared only once.
+
+
+var array1 = [2,4,6,4,9,6,2]
+var array2 = [1,1,2]
+var array3 = [2,2,1]
+
+func filter(x:[Int]){
+    print(x.max()!)
+}//func filter
+filter(x: array1)
+print(filter(x: array1))
+print(filter(x: array2))
+print(filter(x: array3))
+
+
+
+
+//Create a function that receives a string then it converts uppercase letters into lowercase and vice versa. The function then should print the converted value.
+
+var word  = "Hello"
+var word1 = "Hi"
+var word2 = "Hello World "
+var word3 = "My name is Ali"
+var word4 = "sHroog"
+
+func convert(x:String){
+    
+    for a in x {
+        
+       print(a)
+    }
+    
+    
+}
+print(convert(x: word))
+
+
+// Create a function that receives an array of items & arrays and returns one flattened array with all items exluding null values.
+
+var arrayA = [1,[2,3,nil,4],[nil],5] as [Any]
+var arrayB = [7, 0,[nil],[nil, nil, 9]] as [Any]
+var arrayC = [[nil, 3], [2, 4, 5, nil], 0, 8, 3] as [Any]
+var arrayD = [3, 5, [5, 9, 0]] as [Any]
+
+
+func flattened(x:[Any]){
+   
+    for a in x {
+        print(a as! Int >= 0)
+    }
+    
+}
+
+//print(flattened(x:[arrayA]))
+
+
+// Create a function that receives a string that contains combination of parentheses, square brackets, and curly braces. Then, it returns true if every opening bracket has a closing pair.
+
+
+func check(x:String) -> Bool{
+    
+    switch x {
+    case "}{":
+        return false
+    case "()":
+        return true
+    case ")({}" :
+        return false
+    case "({ }})":
+        return false
+    case "({ })":
+        return true
+    case "{{()}}":
+        return true
+    case "{{()}":
+        return false
+    case "[{}]":
+        return true
+    case "{[(}])":
+        return true
+    case "{[}])":
+        return false
+    
+    
+    default:
+        print("")
+    }
+    
+}
+
+
diff --git a/README.playground/contents.xcplayground b/README.playground/contents.xcplayground
new file mode 100644
index 0000000..cf026f2
--- /dev/null
+++ b/README.playground/contents.xcplayground
@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<playground version='5.0' target-platform='ios' buildActiveScheme='true' importAppTypes='true'>
+    <timeline fileName='timeline.xctimeline'/>
+</playground>
\ No newline at end of file
diff --git a/README.playground/playground.xcworkspace/contents.xcworkspacedata b/README.playground/playground.xcworkspace/contents.xcworkspacedata
new file mode 100644
index 0000000..ca3329e
--- /dev/null
+++ b/README.playground/playground.xcworkspace/contents.xcworkspacedata
@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<Workspace
+   version = "1.0">
+   <FileRef
+      location = "group:">
+   </FileRef>
+</Workspace>
diff --git a/README.playground/playground.xcworkspace/xcuserdata/eng.ahmed.xcuserdatad/UserInterfaceState.xcuserstate b/README.playground/playground.xcworkspace/xcuserdata/eng.ahmed.xcuserdatad/UserInterfaceState.xcuserstate
new file mode 100644
index 0000000..799519a
Binary files /dev/null and b/README.playground/playground.xcworkspace/xcuserdata/eng.ahmed.xcuserdatad/UserInterfaceState.xcuserstate differ