Building android app

when i tried to build the app on unity i gives me the following errors i dont understand why ///////////////////////////////////////////////////////////////////////////////////////// 1. Win32Exception: ApplicationName='C:/Users/xxxx/Downloads/sdk-tools-windows-3859397\platform-tools\aapt.exe', CommandLine='package --auto-add-overlay -v -f -m -J "gen" -M "AndroidManifest.xml" -S "res" -I "C:/Users/xxxx/Downloads/sdk-tools-windows-3859397\platforms\android-23\android.jar" -F bin/resources.ap_', CurrentDirectory='Temp/StagingArea' System.Diagnostics.Process.Start_noshell (System.Diagnostics.ProcessStartInfo startInfo, System.Diagnostics.Process process) System.Diagnostics.Process.Start_common (System.Diagnostics.ProcessStartInfo startInfo, System.Diagnostics.Process process) System.Diagnostics.Process.Start () (wrapper remoting-invoke-with-check) System.Diagnostics.Process:Start () UnityEditor.Utils.Program.Start (System.EventHandler exitCallback) (at C:/buildslave/unity/build/E

///////////////////////////////////////////////////////////////////////////////////////// 2. Build completed with a result of 'Failed' UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)

/////////////////////////////////////////////////////////////////////////////////////////// 3. UnityEditor.BuildPlayerWindow+BuildMethodException: 3 errors at UnityEditor.BuildPlayerWindow+DefaultBuildMethods.BuildPlayer (BuildPlayerOptions options) [0x00207] in C:\buildslave\unity\build\Editor\Mono\BuildPlayerWindowBuildMethods.cs:172 at UnityEditor.BuildPlayerWindow.CallBuildMethods (Boolean askForBuildLocation, BuildOptions defaultBuildOptions) [0x00050] in C:\buildslave\unity\build\Editor\Mono\BuildPlayerWindowBuildMethods.cs:83 UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)