You are given a string s of length n consisting only of lowercase Latin letters.

A substring of a string is a contiguous subsequence of that string. So, string "forces" is substring of string "codeforces", but string "coder" is not.

Your task is to calculate the number of ways to remove exactly one substring from this string in such a way that all remaining characters are equal (the number of distinct characters either zero or one).

It is guaranteed that there is at least two different characters in s.

Note that you can remove the whole string and it is correct. Also note that you should remove at least one character.

Since the answer can be rather large (not very large though) print it modulo 998244353.

If you are Python programmer, consider using PyPy instead of Python when you submit your code.

Input

The first line of the input contains one integer n (2 ≤ n ≤ 2 ⋅ 10^5) — the length of the string s.

The second line of the input contains the string s of length n consisting only of lowercase Latin letters.

It is guaranteed that there is at least two different characters in s.

Output

Print one integer — the number of ways modulo 998244353 to remove exactly one substring from s in such way that all remaining characters are equal.

Examples

Input


4
abaa


Output


6


Input


7
aacdeee


Output


6

Input


2
az


Output


3

Note

Let s[l; r] be the substring of s from the position l to the position r inclusive.

Then in the first example you can remove the following substrings: 

  * s[1; 2]; 
  * s[1; 3]; 
  * s[1; 4]; 
  * s[2; 2]; 
  * s[2; 3]; 
  * s[2; 4]. 



In the second example you can remove the following substrings: 

  * s[1; 4]; 
  * s[1; 5]; 
  * s[1; 6]; 
  * s[1; 7]; 
  * s[2; 7]; 
  * s[3; 7]. 



In the third example you can remove the following substrings: 

  * s[1; 1]; 
  * s[1; 2]; 
  * s[2; 2]. 
#!/usr/bin/env python
"""
This file is part of https://github.com/Cheran-Senthil/PyRival.

Copyright 2018 Cheran Senthilkumar all rights reserved,
Cheran Senthilkumar <hello@cheran.io>
Permission to use, modify, and distribute this software is given under the
terms of the MIT License.

"""
from __future__ import division, print_function

import cmath
import itertools
import math
import operator as op
# import random
import sys
from atexit import register
from bisect import bisect_left, bisect_right
# from collections import Counter, MutableSequence, defaultdict, deque
# from copy import deepcopy
# from decimal import Decimal
# from difflib import SequenceMatcher
# from fractions import Fraction
# from heapq import heappop, heappush

if sys.version_info[0] < 3:
    # from cPickle import dumps
    from io import BytesIO as stream
    # from Queue import PriorityQueue, Queue
else:
    # from functools import reduce
    from io import StringIO as stream
    from math import gcd
    # from pickle import dumps
    # from queue import PriorityQueue, Queue


if sys.version_info[0] < 3:
    class dict(dict):
        """dict() -> new empty dictionary"""
        def items(self):
            """D.items() -> a set-like object providing a view on D's items"""
            return dict.iteritems(self)

        def keys(self):
            """D.keys() -> a set-like object providing a view on D's keys"""
            return dict.iterkeys(self)

        def values(self):
            """D.values() -> an object providing a view on D's values"""
            return dict.itervalues(self)

    def gcd(x, y):
        """greatest common divisor of x and y"""
        while y:
            x, y = y, x % y
        return x

    input = raw_input
    range = xrange

    filter = itertools.ifilter
    map = itertools.imap
    zip = itertools.izip


def sync_with_stdio(sync=True):
    """Set whether the standard Python streams are allowed to buffer their I/O.

    Args:
        sync (bool, optional): The new synchronization setting.

    """
    global input, flush

    if sync:
        flush = sys.stdout.flush
    else:
        sys.stdin = stream(sys.stdin.read())
        input = lambda: sys.stdin.readline().rstrip('\r\n')

        sys.stdout = stream()
        register(lambda: sys.__stdout__.write(sys.stdout.getvalue()))


def main():
    n = int(input())
    s = input()

    first = s[0]
    last = s[-1]

    for i in range(n):
        l = i
        if s[i] != first:
            break

    for i in range(n):
        r = i
        if s[-1 - i] != last:
            break

    if first == last:
        print(((l + 1) * (r + 1)) % 998244353)
    else:
        print((l + r + 1) % 998244353)


if __name__ == '__main__':
    sync_with_stdio(False)
    main()
