/** Fonction minimum, min( Exp, Exp). */
public class ExpFmin extends Exp {
  public Exp e1, e2;
  public ExpFmin(Exp e1, Exp e2) {
    super(e1, e2); this.e1 = e1; this.e2 = e2;
  }
  public Integer eval() {
    int i1 = e1.eval();
    int i2 = e2.eval();
    return (i1<i2)?i1:i2;
  }
}