# UUID: 4ebfc3ce-e1c4-4cc3-9fc0-fd83148dbb46
n = int(input())
arr = list(map(int, input().split()))

min_right = [0] * n
min_right[-1] = arr[-1]
for i in range(n - 2, -1, -1):
    min_right[i] = min(arr[i], min_right[i + 1])

i = 0
j = n - 1
max_dist = -1
best_i = best_j = -1

while i < n and j > i:
    if arr[i] > min_right[j]:
        if j - i > max_dist:
            max_dist = j - i
            best_i = i + 1
            best_j = j + 1
        i += 1
    else:
        j -= 1

if max_dist == -1:
    print(-1)
else:
    print(best_i, best_j)