Which of these is exponential?

public static int one(int[] tab) { int n = tab.length; return one_aux(tab, 0, n - 1); } public static int one_aux(int[] tab, int lo, int hi) { if (hi - lo tab[mid + 1]) return three_aux(tab, mid + 1, hi) + 2 * tab[mid]; else return three_aux tab[mid + 1]) return four_aux(tab, lo + 1, hi) + 2 * tab[mid]; else return four_aux(tab, lo, hi - 1) + 2 * tab[mid + 1]; }