Build Settings Error

 'm finishing an app and on the build settings it give me this error.

 Error building Player: CommandInvokationFailure: Unable to merge android manifests. See the Console for more details.
 C:\Program Files (x86)\Java\jdk1.8.0_05\bin\java.exe -Xmx1024M -Dcom.android.sdkmanager.toolsdir="C:/Program Files (x86)/sdk\tools" -Dfile.encoding=UTF8 -jar "C:/Program Files (x86)/Unity/Editor/Data/BuildTargetTools/AndroidPlayer\sdktools.jar" -

 stderr[

 ]
 stdout[
 Warning: [AndroidManifest-main.xml:25, AndroidManifest.xml:3] Main manifest has <uses-sdk android:targetSdkVersion='18'> but library uses targetSdkVersion='19'
 ]