A8015. Spoilt Permutation

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.

If it is impossible to obtain the given permutation from the original one in exactly one action, print 0 0. Otherwise, print two numbers $l$ $r$ ( $1<=l<r<=n$ ) which are the endpoints of the segment that needs to be reversed to obtain from permutation 1 2 ... $n$ the given one.