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.
#!/usr/bin/env python3
import sys, getpass
import math, random
import functools, itertools, collections, heapq, bisect
from collections import Counter, defaultdict, deque
input = sys.stdin.readline  # to read input quickly

# available on Google, AtCoder Python3, not available on Codeforces
# import numpy as np
# import scipy

M9 = 10**9 + 7  # 998244353
# d4 = [(1,0),(0,1),(-1,0),(0,-1)]
# d8 = [(1,0),(1,1),(0,1),(-1,1),(-1,0),(-1,-1),(0,-1),(1,-1)]
# d6 = [(2,0),(1,1),(-1,1),(-2,0),(-1,-1),(1,-1)]  # hexagonal layout
MAXINT = sys.maxsize

# if testing locally, print to terminal with a different color
OFFLINE_TEST = getpass.getuser() == "hkmac"
# OFFLINE_TEST = False  # codechef does not allow getpass
def log(*args):
    if OFFLINE_TEST:
        print('\033[36m', *args, '\033[0m', file=sys.stderr)

def solve(*args):
    # screen input
    if OFFLINE_TEST:
        log("----- solving ------")
        log(*args)
        log("----- ------- ------")
    return solve_(*args)

def read_matrix(rows):
    return [list(map(int,input().split())) for _ in range(rows)]

def read_strings(rows):
    return [input().strip() for _ in range(rows)]

# ---------------------------- template ends here ----------------------------


def solve_():
    # your solution here
    n,m = map(int,input().split())
    a = list(map(int,input().split()))
    b = [a[0]]
    for i in range(m-1):
        if a[i+1]<a[i]:
            b.append(b[i]+a[i+1]-a[i]+n)
        else:
            b.append(b[i]+a[i+1]-a[i])
    # print(b)
    return b[-1]-1
        

for case_num in [0]:  # no loop over test case
# for case_num in range(100):  # if the number of test cases is specified
# for case_num in range(int(input())):

    # read line as an integer
    # k = int(input())

    # read line as a string
    # srr = input().strip()

    # read one line and parse each word as a string
    # lst = input().split()
    
    # read one line and parse each word as an integer
    # a,b,c = list(map(int,input().split()))
    # arr = list(map(int,input().split()))
    # brr = list(map(int,input().split()))

    # read multiple rows
    # mrr = read_matrix(k)  # and return as a list of list of int
    # arr = read_strings(k)  # and return as a list of str

    res = solve()  # include input here
    
    # print result
    # Google and Facebook - case number required
    # print("Case #{}: {}".format(case_num+1, res))

    # Other platforms - no case number required
    
    print(res)
    
    # print(len(res))
    # print(*res)  # print a list with elements
    # for r in res:  # print each list in a different line
        # print(res)
        # print(*res)