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 a[1010], b[1010];
int main() {
  int n;
  int t1 = 0, t2 = 0, num = 0;
  int k = 1;
  scanf("%d", &n);
  for (int i = 1; i <= n; i++) scanf("%d", &a[i]);
  for (int i = 1; i < n; i++) {
    if (a[i + 1] > a[i] + 1) {
      t1 = i + 1;
      num = a[i + 1];
      break;
    }
    if (a[i + 1] == a[i] - 1) {
      t1 = i;
      num = a[i];
      break;
    }
  }
  for (int i = t1 + 1; i <= n; i++) {
    if (a[i] == a[t1] + 1) {
      t2 = i - 1;
      break;
    }
    if (i == n && t2 == 0) {
      t2 = n;
      break;
    }
  }
  for (int i = t1; i < t2; i++)
    if (a[i] != a[i + 1] + 1) {
      k = 0;
      break;
    }
  for (int i = 1; i < t1 - 1; i++)
    if (a[i] + 1 != a[i + 1]) {
      k = 0;
      break;
    }
  for (int i = t2 + 1; i < n; i++)
    if (a[i] + 1 != a[i + 1]) {
      k = 0;
      break;
    }
  if (k == 0)
    cout << "0 0";
  else
    cout << t1 << " " << t2;
}