public boolean swiftLeft(int idUser, boolean pickup) {
		int passengers = 0;
		int i = 0, j = 0;
		Action a;
		Action n = new Action(idUser, pickup);
		
		for (i = 0; i < size(); ++i) {				//Encontrar la acción
			a = get(i);
			
			if (a.idUser == idUser && a.isPickup == pickup) break;
			else if (a.isPickup) ++passengers;
			else --passengers;
		}
		
		for (j = i-1; j > 0; --j) {					//Encontrar una posición válida
			a = get(j);
			
			if (a.idUser == idUser) break;
			else if (a.isPickup) --passengers;
			else ++passengers;
			
			if (!pickup || passengers < 3) {
				add(j, n);
				remove(i);
				return true;
			}
		}
		return false;
	}