Problem: This is the first subtask of problem F. The only differences between this and the second subtask are the constraints on the value of m and the time limit. You need to solve both subtasks in order to hack this one.

There are n+1 distinct colours in the universe, numbered 0 through n. There is a strip of paper m centimetres long initially painted with colour 0. 

Alice took a brush and painted the strip using the following process. For each i from 1 to n, in this order, she picks two integers 0 ≤ a_i < b_i ≤ m, such that the segment [a_i, b_i] is currently painted with a single colour, and repaints it with colour i. 

Alice chose the segments in such a way that each centimetre is now painted in some colour other than 0. Formally, the segment [i-1, i] is painted with colour c_i (c_i ≠ 0). Every colour other than 0 is visible on the strip.

Count the number of different pairs of sequences \\{a_i\}_{i=1}^n, \\{b_i\}_{i=1}^n that result in this configuration. 

Since this number may be large, output it modulo 998244353.

Input

The first line contains a two integers n, m (1 ≤ n ≤ 500, n = m) — the number of colours excluding the colour 0 and the length of the paper, respectively.

The second line contains m space separated integers c_1, c_2, …, c_m (1 ≤ c_i ≤ n) — the colour visible on the segment [i-1, i] after the process ends. It is guaranteed that for all j between 1 and n there is an index k such that c_k = j.

Note that since in this subtask n = m, this means that c is a permutation of integers 1 through n.

Output

Output a single integer — the number of ways Alice can perform the painting, modulo 998244353.

Examples

Input


3 3
1 2 3


Output


5


Input


7 7
4 5 1 6 2 3 7


Output


165

Note

In the first example, there are 5 ways, all depicted in the figure below. Here, 0 is white, 1 is red, 2 is green and 3 is blue.

<image>

Below is an example of a painting process that is not valid, as in the second step the segment 1 3 is not single colour, and thus may not be repainted with colour 2.

<image>

Solution (in JAVA):

Solution:
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.*;
import java.util.concurrent.ThreadLocalRandom;

public class Main2 {

    static long mod = 998244353;
    static FastScanner scanner;
    static int[] a;
    static int[] pos;

    static Map<Integer, Long> memo = new HashMap<>();

    public static void main(String[] args) {
        scanner = new FastScanner();
        int n = scanner.nextInt();
        int m = scanner.nextInt();
        a = scanner.nextIntArray(n);
        pos = new int[n + 10];
        for (int i = 0; i < n; i++) pos[a[i]] = i;
        System.out.println(fill(0, n -1));
    }

    static long fill(int s, int e) {
        if (e < s) return 1;
        if (s == e) return 1;
        if (memo.containsKey(s * 10000 + e)) return memo.get(s * 10000 + e);

        int toFill = 100000;
        for (int i = s; i <= e; i++) toFill = Math.min(a[i], toFill);

        long resEnd = 0;
        for (int i = pos[toFill]; i <= e; i++) {
            resEnd = (resEnd + mulMod(fill(pos[toFill] + 1, i), fill(i + 1, e))) % mod;
        }

        long resStart = 0;
        for (int i = s - 1; i < pos[toFill]; i++) {
            resStart = (resStart + mulMod(resEnd, fill(s, i), fill(i + 1, pos[toFill] - 1))) % mod;
        }
        long res = resStart;
        memo.put(s * 10000 + e, res);
        return res;
    }

    static long mulMod(long... a) {
        long res = 1;
        for (int i = 0; i < a.length; i++) {
            res = (res * a[i]) % mod;
        }
        return res;
    }

    static int[][] nextPos(String a) {
        int[][] result = new int[a.length()][3];
        for (int i = 0; i < a.length(); i++)
            for (int j = 0; j < 3; j++) result[i][j] = -1;

        for (int i = a.length() - 1; i >= 0; i--) {
            if (i != a.length() - 1) {
                result[i][0] = result[i + 1][0];
                result[i][1] = result[i + 1][1];
                result[i][2] = result[i + 1][2];
            }
            result[i][a.charAt(i) - 'a'] = i;
        }
        return result;
    }

    static int[][] nextPosBack(String a) {
        int[][] result = new int[a.length()][3];
        for (int i = 0; i < a.length(); i++)
            for (int j = 0; j < 3; j++) result[i][j] = -1;

        for (int i = 0; i < a.length(); i++) {
            if (i != 0) {
                result[i][0] = result[i - 1][0];
                result[i][1] = result[i - 1][1];
                result[i][2] = result[i - 1][2];
            }
            result[i][a.charAt(i) - 'a'] = i;
        }
        return result;
    }

    static class WithIdx implements Comparable<WithIdx>{
        int val, idx;

        public WithIdx(int val, int idx) {
            this.val = val;
            this.idx = idx;
        }

        @Override
        public int compareTo(WithIdx o) {
            return Integer.compare(val, o.val);
        }
    }

    public static class FastScanner {
        BufferedReader br;
        StringTokenizer st;

        public FastScanner() {
            br = new BufferedReader(new InputStreamReader(System.in));
        }

        String nextToken() {
            while (st == null || !st.hasMoreElements()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        String nextLine() {
            try {
                return br.readLine();
            } catch (Exception e) {
                e.printStackTrace();
                throw new RuntimeException();
            }
        }

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

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

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

        int[] nextIntArray(int n) {
            int[] res = new int[n];
            for (int i = 0; i < n; i++) res[i] = nextInt();
            return res;
        }

        long[] nextLongArray(int n) {
            long[] res = new long[n];
            for (int i = 0; i < n; i++) res[i] = nextLong();
            return res;
        }

        String[] nextStringArray(int n) {
            String[] res = new String[n];
            for (int i = 0; i < n; i++) res[i] = nextToken();
            return res;
        }
    }

    static class PrefixSums {
        long[] sums;

        public PrefixSums(long[] sums) {
            this.sums = sums;
        }

        public long sum(int fromInclusive, int toExclusive) {
            if (fromInclusive > toExclusive) throw new IllegalArgumentException("Wrong value");
            return sums[toExclusive] - sums[fromInclusive];
        }

        public static PrefixSums of(int[] ar) {
            long[] sums = new long[ar.length + 1];
            for (int i = 1; i <= ar.length; i++) {
                sums[i] = sums[i - 1] + ar[i - 1];
            }
            return new PrefixSums(sums);
        }

        public static PrefixSums of(long[] ar) {
            long[] sums = new long[ar.length + 1];
            for (int i = 1; i <= ar.length; i++) {
                sums[i] = sums[i - 1] + ar[i - 1];
            }
            return new PrefixSums(sums);
        }
    }

    static class ADUtils {
        static void sort(int[] ar) {
            Random rnd = ThreadLocalRandom.current();
            for (int i = ar.length - 1; i > 0; i--)
            {
                int index = rnd.nextInt(i + 1);
                // Simple swap
                int a = ar[index];
                ar[index] = ar[i];
                ar[i] = a;
            }
            Arrays.sort(ar);
        }

        static void reverse(int[] arr) {
            int last = arr.length / 2;
            for (int i = 0; i < last; i++) {
                int tmp = arr[i];
                arr[i] = arr[arr.length - 1 - i];
                arr[arr.length - 1 - i] = tmp;
            }
        }

        static void sort(long[] ar) {
            Random rnd = ThreadLocalRandom.current();
            for (int i = ar.length - 1; i > 0; i--)
            {
                int index = rnd.nextInt(i + 1);
                // Simple swap
                long a = ar[index];
                ar[index] = ar[i];
                ar[i] = a;
            }
            Arrays.sort(ar);
        }
    }

    static class MathUtils {
        static long[] FIRST_PRIMES = {
                2,     3,      5,      7,     11,     13,     17,     19,     23,     29,
                31,     37,     41,     43,     47,     53,     59,     61,     67,     71,
                73,     79,     83,     89  ,   97 ,    101,    103,    107,    109,    113,
                127,    131,    137,    139,    149,    151,    157,    163,    167,    173,
                179,    181,    191,    193,    197,    199,    211,    223,    227,    229,
                233,    239,    241,    251,    257,    263,    269,    271,    277,    281,
                283,    293,    307,    311,    313,    317,    331,    337,    347,    349,
                353,    359,    367,    373,    379,    383,    389,    397,    401,    409,
                419,    421,    431,    433,    439,    443,    449,    457,    461,    463,
                467,    479,    487,    491,    499,    503,    509,    521,    523,    541,
                547,    557,    563,    569,    571,    577,    587,    593,    599,    601,
                607,    613,    617,    619,    631,    641,    643,    647,    653,    659,
                661,    673,    677,    683,    691,    701,    709,    719,    727,    733,
                739,    743,    751,    757,    761,    769,    773,    787,    797,    809,
                811,    821,    823,    827,    829,    839,    853,    857,    859,    863,
                877,    881,    883,    887,    907,    911,    919,    929,    937,    941,
                947,    953,    967,    971,    977,    983,    991,    997,   1009,   1013,
                1019,   1021,   1031,   1033,   1039,   1049,   1051};

        static long[] primes(int to) {
            long[] all = new long[to + 1];
            long[] primes = new long[to + 1];
            all[1] = 1;
            int primesLength = 0;
            for (int i = 2; i <= to; i ++) {
                if (all[i] == 0) {
                    primes[primesLength++] = i;
                    all[i] = i;
                }
                for (int j = 0; j < primesLength && i * primes[j] <= to && all[i] >= primes[j]; j++) {
                    all[(int) (i * primes[j])] = primes[j];
                }
            }
            return Arrays.copyOf(primes, primesLength);
        }

        static long modpow(long b, long e, long m) {
            long result = 1;

            while (e > 0) {
                if ((e & 1) == 1) {
                    /* multiply in this bit's contribution while using modulus to keep
                     * result small */
                    result = (result * b) % m;
                }
                b = (b * b) % m;
                e >>= 1;
            }

            return result;
        }

        static long submod(long x, long y, long m) {
            return (x - y + m) % m;
        }
    }
}