Xenia lives in a city that has n houses built along the main ringroad. The ringroad houses are numbered 1 through n in the clockwise order. The ringroad traffic is one way and also is clockwise.

Xenia has recently moved into the ringroad house number 1. As a result, she's got m things to do. In order to complete the i-th task, she needs to be in the house number ai and complete all tasks with numbers less than i. Initially, Xenia is in the house number 1, find the minimum time she needs to complete all her tasks if moving from a house to a neighboring one along the ringroad takes one unit of time.

Input

The first line contains two integers n and m (2 ≤ n ≤ 105, 1 ≤ m ≤ 105). The second line contains m integers a1, a2, ..., am (1 ≤ ai ≤ n). Note that Xenia can have multiple consecutive tasks in one house.

Output

Print a single integer — the time Xenia needs to complete all tasks.

Please, do not use the %lld specifier to read or write 64-bit integers in С++. It is preferred to use the cin, cout streams or the %I64d specifier.

Examples

Input

4 3
3 2 3


Output

6


Input

4 3
2 3 3


Output

2

Note

In the first test example the sequence of Xenia's moves along the ringroad looks as follows: 1 → 2 → 3 → 4 → 1 → 2 → 3. This is optimal sequence. So, she needs 6 time units.
"""Template for Python Competitive Programmers prepared by Mayank Chaudhary aka chaudhary_19"""

# to use the print and division function of Python3
from __future__ import division, print_function

"""value of mod"""
MOD = 10 ** 9 + 7

"""use resource"""
# import resource
# resource.setrlimit(resource.RLIMIT_STACK, [0x100000000, resource.RLIM_INFINITY])

"""uncomment next 4 lines while doing recursion based question"""
# import threading
# threading.stack_size(2**27)
import sys

# sys.setrecursionlimit(10**6)

"""uncomment next 7 lines while doing nCr question"""
# fact=[1]
# for i in range(1,100001):
#    fact.append((fact[-1]*i)%mod)
# ifact=[0]*100001
# ifact[100000]=pow(fact[100000],mod-2,mod)
# for i in range(100000,0,-1):
#    ifact[i-1]=(i*ifact[i])%mod

"""uncomment modules according to your need"""
# from bisect import bisect_left as bl# c++ lowerbound bl(array,element)
# from bisect import bisect_right as br  # c++ upperbound
# import itertools
# import collections
# import math
# import heapq
# from random import randint as rn
# from Queue import Queue as Q

'''
def modinv(n, p):
    return pow(n, p - 2, p)
'''

'''
def ncr(n, r, p):  # for using this uncomment the lines calculating fact and ifact
    t = ((fact[n]) * ((ifact[r] * ifact[n - r]) % p)) % p
    return t
'''


def get_ints(): return map(int, sys.stdin.readline().strip().split())


def get_array(): return list(map(int, sys.stdin.readline().strip().split()))


def input(): return sys.stdin.readline().strip()


'''
def GCD(x, y):
    while (y):
        x, y = y, x % y
    return x
'''

"""*******************************************************"""


def main():

    n,m = get_ints()
    Arr = get_array()

    curr = 1
    ans = 0
    for i in Arr:
        if i>=curr:
            ans += (i-curr)
        else:
            ans += (n-curr + i)
        curr = i
    print(ans)




""" -------- Python 2 and 3 footer by Pajenegod and c1729 ---------"""

py2 = round(0.5)
if py2:
    from future_builtins import ascii, filter, hex, map, oct, zip

    range = xrange

import os, sys
from io import IOBase, BytesIO

BUFSIZE = 8192


class FastIO(BytesIO):
    newlines = 0

    def __init__(self, file):
        self._file = file
        self._fd = file.fileno()
        self.writable = "x" in file.mode or "w" in file.mode
        self.write = super(FastIO, self).write if self.writable else None

    def _fill(self):
        s = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE))
        self.seek((self.tell(), self.seek(0, 2), super(FastIO, self).write(s))[0])
        return s

    def read(self):
        while self._fill(): pass
        return super(FastIO, self).read()

    def readline(self):
        while self.newlines == 0:
            s = self._fill();
            self.newlines = s.count(b"\n") + (not s)
        self.newlines -= 1
        return super(FastIO, self).readline()

    def flush(self):
        if self.writable:
            os.write(self._fd, self.getvalue())
            self.truncate(0), self.seek(0)


class IOWrapper(IOBase):
    def __init__(self, file):
        self.buffer = FastIO(file)
        self.flush = self.buffer.flush
        self.writable = self.buffer.writable
        if py2:
            self.write = self.buffer.write
            self.read = self.buffer.read
            self.readline = self.buffer.readline
        else:
            self.write = lambda s: self.buffer.write(s.encode('ascii'))
            self.read = lambda: self.buffer.read().decode('ascii')
            self.readline = lambda: self.buffer.readline().decode('ascii')


sys.stdin, sys.stdout = IOWrapper(sys.stdin), IOWrapper(sys.stdout)
input = lambda: sys.stdin.readline().rstrip('\r\n')

""" main function"""

if __name__ == '__main__':
    main()
# threading.Thread(target=main).start()