There are n psychos standing in a line. Each psycho is assigned a unique integer from 1 to n. At each step every psycho who has an id greater than the psycho to his right (if exists) kills his right neighbor in the line. Note that a psycho might kill and get killed at the same step. 

You're given the initial arrangement of the psychos in the line. Calculate how many steps are needed to the moment of time such, that nobody kills his neighbor after that moment. Look notes to understand the statement more precise.

Input

The first line of input contains integer n denoting the number of psychos, (1 ≤ n ≤ 105). In the second line there will be a list of n space separated distinct integers each in range 1 to n, inclusive — ids of the psychos in the line from left to right.

Output

Print the number of steps, so that the line remains the same afterward.

Examples

Input

10
10 9 7 8 6 5 3 4 2 1


Output

2


Input

6
1 2 3 4 5 6


Output

0

Note

In the first sample line of the psychos transforms as follows: [10 9 7 8 6 5 3 4 2 1]  →  [10 8 4] →  [10]. So, there are two steps.
// ONE DAY, YOU WILL BE BEYOND THE REACH OF SPACE AND TIME. //
// UNTIL THEN, STAY LOW AND CODE HARD. //
// Author :- Saurabh//
//BIT MESRA, RANCHI//
import java.io.*;
import java.util.*;
import static java.lang.Math.*;

public class psychosInLine {

    static void Bolo_Jai_Mata_Di() {

        int n=ni();
        Stack<Integer> s1=new Stack<>();
        Stack<Integer> s2=new Stack<>();
        for(int i=0;i<n;i++)s1.push(ni());
        if(n==1){
            pl(0);return;
        }
        int x=0;int count=1;
        while(count!=0){
//            pl(s1);
//            pl(s2);
            count=0;
            if(x%2==0){
                s2.push(s1.pop());
                while(!s1.isEmpty()){
                    if(s1.peek()>s2.peek()){
                        count++;s2.pop();
                    }
                    s2.push(s1.pop());
                }
            }
            else {
                s1.push(s2.pop());
                while(!s2.isEmpty()){
                    if(s2.peek()<s1.peek()){
                        count++;s1.pop();
                    }
                    s1.push(s2.pop());
                }
            }
            if(count>0)x++;
        }
        pl(x);
//        pl(s1);
//        pl(s2);

        flush();
    }

    /////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
    //THE DON'T CARE ZONE BEGINS HERE...//

    static Calendar ts, te;                                                  //For time calculation
    static int mod9 = 1000000007;
    static int n, m, k, t, mod = 998244353;
    static Lelo input = new Lelo(System.in);
    static PrintWriter pw = new PrintWriter(System.out, true);


    public static void main(String[] args) {      //threading has been used to increase the stack size.

        new Thread(null, null, "BlackRise", 1 << 25)  //the last parameter is stack size desired.,
        {
            public void run() {

                try {
                    tsc();
                    Bolo_Jai_Mata_Di();
                } catch (Exception e) {
                    e.printStackTrace();
                    System.exit(1);
                }
            }
        }.start();
    }

    static class Lelo {                                              //Lelo class for fast input
        private InputStream ayega;
        private byte[] buf = new byte[1024];
        private int curChar;
        private int numChars;
        private SpaceCharFilter filter;

        public Lelo(InputStream ayega) {
            this.ayega = ayega;
        }

        public int read() {
            if (numChars == -1)
                throw new InputMismatchException();

            if (curChar >= numChars) {
                curChar = 0;
                try {
                    numChars = ayega.read(buf);
                } catch (IOException e) {
                    throw new InputMismatchException();
                }

                if (numChars <= 0)
                    return -1;
            }
            return buf[curChar++];
        }

        public String nextLine() {
            BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
            String str = "";
            try {
                str = br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return str;
        }

        public int nextInt() {
            int c = read();

            while (isSpaceChar(c))
                c = read();

            int sgn = 1;

            if (c == '-') {
                sgn = -1;
                c = read();
            }

            int res = 0;
            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            }
            while (!isSpaceChar(c));

            return res * sgn;
        }

        public long nextLong() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            long res = 0;

            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            }
            while (!isSpaceChar(c));
            return res * sgn;
        }

        public double nextDouble() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            double res = 0;
            while (!isSpaceChar(c) && c != '.') {
                if (c == 'e' || c == 'E')
                    return res * Math.pow(10, nextInt());
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            }
            if (c == '.') {
                c = read();
                double m = 1;
                while (!isSpaceChar(c)) {
                    if (c == 'e' || c == 'E')
                        return res * Math.pow(10, nextInt());
                    if (c < '0' || c > '9')
                        throw new InputMismatchException();
                    m /= 10;
                    res += (c - '0') * m;
                    c = read();
                }
            }
            return res * sgn;
        }

        public String readString() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            StringBuilder res = new StringBuilder();
            do {
                res.appendCodePoint(c);
                c = read();
            }
            while (!isSpaceChar(c));

            return res.toString();
        }

        public boolean isSpaceChar(int c) {
            if (filter != null)
                return filter.isSpaceChar(c);
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

        public String next() {
            return readString();
        }

        public interface SpaceCharFilter {
            public boolean isSpaceChar(int ch);
        }
    }

    // functions to take input//
    static int ni() {
        return input.nextInt();
    }

    static long nl() {
        return input.nextLong();
    }

    static double nd() {
        return input.nextDouble();
    }

    static String ns() {
        return input.readString();
    }

    //functions to give output
    static void pl() {
        pw.println();
    }

    static void p(Object o) {
        pw.print(o + " ");
    }

    static void pws(Object o) {
        pw.print(o + "");
    }

    static void pl(Object o) {
        pw.println(o);
    }

    static void tsc()                                          //calculates the starting time of execution
    {
        ts = Calendar.getInstance();
        ts.setTime(new Date());
    }

    static void tec()                                          //calculates the ending time of execution
    {
        te = Calendar.getInstance();
        te.setTime(new Date());
    }

    static void pwt()                                          //prints the time taken for execution
    {
        pw.printf("\nExecution time was :- %f s\n", (te.getTimeInMillis() - ts.getTimeInMillis()) / 1000.00);
    }
    static void sort(int ar[], int n) {
        for (int i = 0; i < n; i++) {
            int ran = (int) (Math.random() * n);
            int temp = ar[i];
            ar[i] = ar[ran];
            ar[ran] = temp;
        }
        Arrays.sort(ar);
    }

    static void sort(long ar[], int n) {
        for (int i = 0; i < n; i++) {
            int ran = (int) (Math.random() * n);
            long temp = ar[i];
            ar[i] = ar[ran];
            ar[ran] = temp;
        }
        Arrays.sort(ar);
    }

    static void sort(char ar[], int n) {
        for (int i = 0; i < n; i++) {
            int ran = (int) (Math.random() * n);
            char temp = ar[i];
            ar[i] = ar[ran];
            ar[ran] = temp;
        }
        Arrays.sort(ar);
    }
    static void flush() {
        tec();                  //ending time of execution
        //pwt();                //prints the time taken to execute the program
        pw.flush();
        pw.close();
    }
}