added ex O

src/exercises/ex_o/NumberConsumer.java

@@ -0,0 +1,16 @@
+package exercises.ex_o;
+
+public class NumberConsumer implements Runnable {
+    private LockedWithConditionsStack stack;
+
+    public NumberConsumer(LockedWithConditionsStack stack) {
+        this.stack = stack;
+    }
+
+    @Override
+    public void run() {
+        while (true) {
+            System.out.println("Pop from stack: " + stack.popFromStack());
+        }
+    }
+}