Vasya collects coins: he has exactly one coin for every year from 1 to *n*. Naturally, Vasya keeps all the coins in his collection in the order in which they were released. Once Vasya's younger brother made a change — he took all the coins whose release year dated from *l* to *r* inclusively and put them in the reverse order. That is, he took a certain segment [*l*, *r*] and reversed it. At that the segment's endpoints did not coincide. For example, if *n* = 8, then initially Vasya's coins were kept in the order 1 2 3 4 5 6 7 8. If Vasya's younger brother chose the segment [2, 6], then after the reversal the coin order will change to 1 6 5 4 3 2 7 8. Vasya suspects that someone else could have spoilt the permutation after his brother. Help him to find that out. Check if the given permutation can be obtained from the permutation 1 2 ... *n* using exactly one segment reversal. If it is possible, find the segment itself.
The first line contains an integer *n* (1 ≤ *n* ≤ 1000) which is the number of coins in Vasya's collection. The second line contains space-separated *n* integers which are the spoilt sequence of coins. It is guaranteed that the given sequence is a permutation, i.e. it contains only integers from 1 to *n*, and every number is used exactly 1 time.
#in the name of god
#cf,ramezani
#http://codeforces.com/problemset/problem/56/B
n = int(input())
liststr = input().split(" ")
list = [int(l) for l in liststr]
cnt = 1
dovomi = 0
gavali = 0
flag = True

for i in range (-1,n) :
    if i == -1 :
        g = 0
        d = list[i+1]
    elif i == n-1 :
        g = list[i]
        d = n+1
    else :
        g = list[i]
        d = list[i+1]
        
    if cnt == 1 :
        if g+1 < d :
            cnt = 2
            dovomi = d
        elif g+1 > d :
            flag = False
            break
    elif cnt == 2 :
        if g-1 < d :
            cnt = 3
            gavali = g
        elif g-1 > d :
            flag = False
            break
    elif cnt == 3 :
        if g+1 != d :
            flag = False
            break
            
if flag :
    print(str(gavali) + " " + str(dovomi))
else :
    print("0 0")
        
