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;
  int arr[n];
  for (int i = 0; i < n; i++) cin >> arr[i];
  bool possible = 1;
  int situation = 0, start, end = -1;
  for (int i = 1; i < n; i++) {
    if (!situation) {
      if (arr[i] == arr[i - 1] + 1)
        continue;
      else if (arr[i] > arr[i - 1]) {
        situation = 1;
        start = i;
      } else if (arr[i] == arr[i - 1] - 1) {
        situation = 1;
        start = i - 1;
      } else
        possible = 0;
    } else if (situation == 1) {
      if (arr[i] == arr[i - 1] - 1)
        continue;
      else if (arr[i] > arr[i - 1]) {
        situation = 2;
        end = i - 1;
      } else
        possible = 0;
    } else {
      if (arr[i] == arr[i - 1] + 1)
        continue;
      else
        possible = 0;
    }
  }
  if (!possible || !situation)
    cout << "0 0";
  else if ((start > 0 && end < n - 1 && end > -1 &&
            arr[start] == arr[end + 1] - 1 && arr[end] - 1 == arr[start - 1]) ||
           (start > 0 && end == -1 && arr[start - 1] == arr[n - 1] - 1) ||
           (!start && end > -1 && end < n - 1 &&
            arr[start] == arr[end + 1] + 1) ||
           (!start && end == -1))
    cout << start + 1 << " " << (end == -1 ? n : end + 1);
  else
    cout << "0 0";
  return 0;
}