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.
/*input
4 3
3 2 3


*/
import java.util.*;
import java.lang.*;
import java.io.*;

public class Main
{
	static PrintWriter out;
	static int MOD = 1000000007;
	static FastReader scan;

    /*-------- I/O using short named function ---------*/
	public static String ns(){return scan.next();}
	public static int ni(){return scan.nextInt();}
	public static long nl(){return scan.nextLong();}
	public static double nd(){return scan.nextDouble();}
	public static String nln(){return scan.nextLine();}
	public static void p(Object o){out.print(o);}
	public static void ps(Object o){out.print(o + " ");}
	public static void pn(Object o){out.println(o);}
    /*-------- for output of an array ---------------------*/
     static void iPA(int arr []){
     	 StringBuilder output = new StringBuilder();
	     for(int i=0; i<arr.length; i++)output.append(arr[i] + " ");out.println(output);
	}
	static void lPA(long arr []){
	     StringBuilder output = new StringBuilder();
	     for(int i=0; i<arr.length; i++)output.append(arr[i] + " ");out.println(output);
	}
	static void sPA(String arr []){
	     StringBuilder output = new StringBuilder();
	     for(int i=0; i<arr.length; i++)output.append(arr[i] + " ");out.println(output);
	}
	static void dPA(double arr []){
	     StringBuilder output = new StringBuilder();
	     for(int i=0; i<arr.length; i++)output.append(arr[i] + " ");out.println(output);
	}
    /*-------------- for input in an array ---------------------*/
	static void iIA(int arr[]){
	     for(int i=0; i<arr.length; i++)arr[i] = ni();
	}
	static void lIA(long arr[]){
	     for(int i=0; i<arr.length; i++)arr[i] = nl(); 
	}
	static void sIA(String arr[]){
	     for(int i=0; i<arr.length; i++)arr[i] = ns(); 
	}
	static void dIA(double arr[]){
	     for(int i=0; i<arr.length; i++)arr[i] = nd();
	}
	/*------------ for taking input faster ----------------*/
     static class FastReader
	{
		BufferedReader br;
		StringTokenizer st;

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

		String next()
		{
			while (st == null || !st.hasMoreElements())
			{
				try
				{
					st = new StringTokenizer(br.readLine());
				}
				catch (IOException e)
				{
					e.printStackTrace();
				}
			}
			return st.nextToken();
		}

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

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

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

		String nextLine()
		{
			String str = "";
			try
			{
				str = br.readLine();
			}
			catch (IOException e)
			{
				e.printStackTrace();
			}
			return str;
		}
	}

	// Method to check if x is power of 2
    static boolean isPowerOfTwo (int x) { return x!=0 && ((x&(x-1)) == 0);}
    //Method to return lcm of two numbers
    static int gcd(int a, int b){return a==0?b:gcd(b % a, a); }
    //Method to count digit of a number
    static int countDigit(long n){return (int)Math.floor(Math.log10(n) + 1);}

    //Method for sorting
	static void ruffle_sort(int[] a) {
		//shandom_ruffle
		Random r=new Random();
		int n=a.length;
		for (int i=0; i<n; i++) {
			int oi=r.nextInt(n);
			int temp=a[i];
			a[i]=a[oi];
			a[oi]=temp;
		}
		//sort
		Arrays.sort(a);
	}
	//Method for checking if a number is prime or not
	static boolean isPrime(int n) { 
        if (n <= 1) return false; 
        if (n <= 3) return true; 
        if (n % 2 == 0 || n % 3 == 0) return false; 
        for (int i = 5; i * i <= n; i = i + 6) 
            if (n % i == 0 || n % (i + 2) == 0) 
            return false; 
        return true; 
    } 

	public static void main (String[] args) throws java.lang.Exception
	{
		OutputStream outputStream =System.out;
        out =new PrintWriter(outputStream);
        scan =new FastReader();
		//for fast output sometimes
		StringBuilder sb = new StringBuilder();
		int n = ni(), m = ni();
		int arr[] = new int[m];
		iIA(arr);
		int intitial = n;
		long sum=0;
		for(int i=0; i<m-1; i++){
			if(arr[i]>arr[i+1]){
				sum += (n-intitial+arr[i]);
				intitial = arr[i];
			}
		}
		sum += (n-intitial+arr[m-1]);
		pn(sum-1);
        out.flush();
		out.close();
	}
	
}

