#be = open("in.1")
#n = int(be.readline())
#lista = list(map(int,be.readline().split()))

n = int(input())
lista = list(map(int,input().split()))
min = []
aktmin = lista[-1]
for i in range(n-1,-1,-1):
    if lista[i] < aktmin:
        aktmin = lista[i]
    min.append(aktmin)
min.reverse()
if lista == min:
    print(-1)
else:
    tav = 0
    for i in range(n-1):
        if i+tav < n and lista[i] > min[i+tav]:
            j = i+tav
            while j < n and min[j] < lista[i]:
                j += 1
            if j-i-1 > tav:
                tav = j - i - 1
                elso = i+1
                utolso = j
    print(elso,utolso)