# UUID: c3df4949-56d3-4a16-a245-7590a216fbcf
n = int(input())
a = list(map(int, input().split()))

min_val = a[-1]
min_idx = n - 1
min_right = [(a[-1], n - 1)] * n

for i in range(n - 2, -1, -1):
    if a[i] < min_val:
        min_val = a[i]
        min_idx = i
    min_right[i] = (min_val, min_idx)

max_dist = -1
i_ans = j_ans = -1

for i in range(n - 1):
    val, j = min_right[i + 1]
    if a[i] > val:
        dist = j - i
        if dist > max_dist:
            max_dist = dist
            i_ans = i + 1
            j_ans = j + 1

if max_dist == -1:
    print(-1)
else:
    print(i_ans, j_ans)