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 JAVA):

Solution:
/**
 * Created by IntelliJ IDEA.
 * User: shakhov
 * Date: 15.06.2011
 * Time: 15:22:46
 * To change this template use File | Settings | File Templates.
 */

//6
//86 402 133 524 405 610   6 4 1

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.io.Reader;
import java.io.Writer;
import java.util.ArrayList;
import java.util.List;
import java.util.StringTokenizer;

public class CodeForces {

	public void solve() throws IOException {
			int n=nextInt();
			int[] arr=new int[n];
			for(int i=0;i<n;i++){
				arr[i]=nextInt();
			}
			int l=-1,r=-1;
			int isFound=0;
			if(arr[0]!=1){
				isFound++;
				l=1;
				if(arr[1]-arr[0]>-1) isFound=3;
			}
			for(int i=1;i<n;i++){
				if(Math.abs(arr[i]-arr[i-1])!=1){
					isFound++;
					if(l==-1) l=i+1;
					else r=i;
				}
			}
			if(isFound==1){
				isFound++;
				r=n;
			}
			
			
			
			if(isFound==2){
				out.println(l+ " "+r);
			} else {
				out.println("0 0");
			}
			
			
	}

	private BufferedReader reader;
	private StringTokenizer tokenizer;
	private String separator;
	public PrintWriter out;

	public static void main(String[] args) {
		new CodeForces().run(new InputStreamReader(System.in), new OutputStreamWriter(System.out));
	}

	public void run(Reader reader, Writer writer) {
		try {
			this.reader = new BufferedReader(reader);
			out = new PrintWriter(writer);
			tokenizer = new StringTokenizer("");
			separator = System.getProperty("line.separator");
			separator = Character.toString(separator.charAt(separator.length() - 1));
			long t1 = System.currentTimeMillis();
			solve();
			out.flush();
			reader.close();
			writer.close();
			long t2 = System.currentTimeMillis();
			System.err.println("Time = " + (t2 - t1));
		} catch (Exception e) {
			e.printStackTrace();
			System.exit(1);
		}
	}

	int nextInt() throws IOException {
		return Integer.parseInt(nextToken());
	}

	long nextLong() throws IOException {
		return Long.parseLong(nextToken());
	}

	double nextDouble() throws IOException {
		return Double.parseDouble(nextToken());
	}

	String nextToken() throws IOException {
		while (tokenizer == null || !tokenizer.hasMoreTokens()) {
			tokenizer = new StringTokenizer(reader.readLine());
		}
		return tokenizer.nextToken();
	}
}