Cannot build project in Android Studio

Cannot build project in Android Studio

I am unable to build my project in Android Studio. I get the following error:
Error:Android Dex: [RaditazAndroid] Unable to execute DX Error:Android
Dex: [RaditazAndroid] com.android.dx.util.DexException: Multiple dex files
define
Landroid/support/v4/accessibilityservice/AccessibilityServiceInfoCompat$AccessibilityServiceInfoVersionImpl;
Error:Android Dex: [RaditazAndroid] at
com.android.dx.merge.DexMerger.readSortableTypes(DexMerger.java:592)
Error:Android Dex: [RaditazAndroid] at
com.android.dx.merge.DexMerger.getSortedTypes(DexMerger.java:550)
Error:Android Dex: [RaditazAndroid] at
com.android.dx.merge.DexMerger.mergeClassDefs(DexMerger.java:531)
Error:Android Dex: [RaditazAndroid] at
com.android.dx.merge.DexMerger.mergeDexBuffers(DexMerger.java:168)
Error:Android Dex: [RaditazAndroid] at
com.android.dx.merge.DexMerger.merge(DexMerger.java:186) Error:Android
Dex: [RaditazAndroid] at
com.android.dx.command.dexer.Main.mergeLibraryDexBuffers(Main.java:300)
Error:Android Dex: [RaditazAndroid] at
com.android.dx.command.dexer.Main.run(Main.java:232) Error:Android Dex:
[RaditazAndroid] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native
Method) Error:Android Dex: [RaditazAndroid] at
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
Error:Android Dex: [RaditazAndroid] at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
Error:Android Dex: [RaditazAndroid] at
java.lang.reflect.Method.invoke(Method.java:597) Error:Android Dex:
[RaditazAndroid] at
org.jetbrains.android.compiler.tools.AndroidDxRunner.runDex(AndroidDxRunner.java:147)
Error:Android Dex: [RaditazAndroid] at
org.jetbrains.android.compiler.tools.AndroidDxRunner.main(AndroidDxRunner.java:276)
Error:Android Dex: [RaditazAndroid] at
com.intellij.rt.execution.CommandLineWrapper.main(CommandLineWrapper.java:121)
However, this error means nothing to me. It does not provide clues as to
where I should begin fixing my project. Has anybody encountered something
similar?
Thanks, Igor