modified:   tp3/tree/Constant.java
	modified:   tp3/tree/Ex1.java
	modified:   tp3/tree/Ex4.java
	new file:   tp3/tree/ExerciceA.java
	new file:   tp3/tree/ExerciceB.java
	modified:   tp3/tree/Expression.java
	modified:   tp3/tree/Operation.java
	new file:   tp3/tree/Polish.java
	modified:   tp3/tree/Variable.java