Java quiz Stacks and Queues need help~

Deque cStack = new ArrayDeque();

cStack.push('A');

cStack.push('B');

cStack.push('C');

System.out.println( cStack.peek( ) ); //what will be printed

cStack.pop( );

System.out.println( cStack.peek( ) ); //what will be printed

cStack.push('D');

cStack.push('E');

cStack.push('F');

System.out.println( cStack.peek( ) ); //what will be printed

cStack.pop( );

cStack.pop( );

cStack.pop( );

cStack.pop( );

System.out.println( cStack.peek( ) ); //what will be printed