Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: -1
	at java.util.ArrayList.elementData(ArrayList.java:418)
	at java.util.ArrayList.get(ArrayList.java:431)
	at DigitalHouseManager.inscribirAlumno(DigitalHouseManager.java:108)
	at Main.main(Main.java:41)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at com.intellij.rt.execution.application.AppMain.main(AppMain.java:147)