Problem: 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.

Input

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.

Output

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.

Examples

Input

8
1 6 5 4 3 2 7 8


Output

2 6


Input

4
2 3 4 1


Output

0 0


Input

4
1 2 3 4


Output

0 0

Solution (in CPP):

Solution:
#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  vector<int> a(n);
  vector<pair<int, int> > pos;
  for (int i = 0; i < n; i++) {
    cin >> a[i];
    if (a[i] == i + 1)
      ;
    else {
      pos.push_back(make_pair(a[i] - i - 1, i + 1));
    }
  }
  if (pos.size() == 0 || pos.size() & 1) {
    cout << "0 0\n";
    return 0;
  }
  bool flg = pos[0].first > 0;
  for (int i = 0; i < pos.size() / 2; i++) {
    if (pos[i].first < 0 && flg || pos[i].first > 0 && !flg ||
        pos[i].first != -pos[pos.size() - i - 1].first) {
      cout << "0 0\n";
      return 0;
    }
  }
  cout << min(pos.back().second, pos[0].second) << " "
       << max(pos.back().second, pos[0].second) << endl;
  return 0;
}