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 = 1005;
int a[maxn];
int n;
int main() {
  scanf("%d", &n);
  memset(a, 0x3f3f3f, sizeof(a));
  for (int i = 1; i <= n; i++) scanf("%d", a + i);
  int cnt = 0, u, v, tmp, ans = 0;
  a[0] = 0;
  for (int i = 1; i <= n; i++) {
    if (i != a[i]) {
      tmp = a[i] - a[i - 1];
      u = i;
      v = a[i];
      for (int j = a[i]; j == a[i]; j--, i++) {
        if (j == a[i]) cnt++;
      }
      if (cnt == tmp)
        ans++, i--;
      else {
        printf("%d %d", 0, 0);
        return 0;
      }
    }
  }
  if (ans == 1)
    printf("%d %d", u, v);
  else
    printf("%d %d", 0, 0);
  return 0;
}