I can't start Hello world on Androids.

[Amritpal]

ERROR: Manifest merger failed with multiple errors, see logs

[Anderson]

Write your activism in the manifest, probably the problem.

<activity
        android:name=".MainActivity"
        android:label="@string/app_name" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
        &lt;category android:name="android.intent.category.LAUNCHER" /&gt;
    &lt;/intent-filter&gt;
&lt;/activity&gt;