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;
const int maxn = 1e3 + 10;
int n, m;
int a[maxn];
void rv(int l, int r) {
  for (int i = l; i <= (l + r) / 2; i++) {
    swap(a[i], a[r + l - i]);
  }
}
int main() {
  scanf("%d", &n);
  for (int i = 1; i <= n; i++) {
    scanf("%d", &a[i]);
  }
  int cnt = 0, l = 0, r = n;
  for (int i = 1; i <= n; i++) {
    ++cnt;
    if (a[i] == cnt) {
      l++;
    } else {
      l++;
      break;
    }
  }
  if (l == n) {
    cout << 0 << " " << 0 << endl;
  } else {
    int cnt = n + 1;
    for (int i = n; i >= 1; i--) {
      --cnt;
      if (a[i] == cnt) {
        r--;
      } else {
        break;
      }
    }
    rv(l, r);
    cnt = 0;
    int l1 = l, r1 = r;
    l = 0, r = n;
    for (int i = 1; i <= n; i++) {
      ++cnt;
      if (a[i] == cnt) {
        l++;
      } else
        break;
    }
    if (l == r) {
      cout << l1 << " " << r1 << endl;
    } else
      cout << 0 << " " << 0 << endl;
  }
  return 0;
}