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.
import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;
 
public class Main
{
    
    static class InputReader {

		private final InputStream stream;
		private final byte[] buf = new byte[8192];
		private int curChar, snumChars;

		public InputReader(InputStream st) {
			this.stream = st;
		}

		public int read() {
			if (snumChars == -1)
				throw new InputMismatchException();
			if (curChar >= snumChars) {
				curChar = 0;
				try {
					snumChars = stream.read(buf);
				} catch (IOException e) {
					throw new InputMismatchException();
				}
				if (snumChars <= 0)
					return -1;
			}
			return buf[curChar++];
		}

		public int ni() {
			int c = read();
			while (isSpaceChar(c)) {
				c = read();
			}
			int sgn = 1;
			if (c == '-') {
				sgn = -1;
				c = read();
			}
			int res = 0;
			do {
				res *= 10;
				res += c - '0';
				c = read();
			} while (!isSpaceChar(c));
			return res * sgn;
		}

		public long nl() {
			int c = read();
			while (isSpaceChar(c)) {
				c = read();
			}
			int sgn = 1;
			if (c == '-') {
				sgn = -1;
				c = read();
			}
			long res = 0;
			do {
				res *= 10;
				res += c - '0';
				c = read();
			} while (!isSpaceChar(c));
			return res * sgn;
		}

		public int[] nia(int n) {
			int a[] = new int[n];
			for (int i = 0; i < n; i++) {
				a[i] = ni();
			}
			return a;
		}

		public String rs() {
			int c = read();
			while (isSpaceChar(c)) {
				c = read();
			}
			StringBuilder res = new StringBuilder();
			do {
				res.appendCodePoint(c);
				c = read();
			} while (!isSpaceChar(c));
			return res.toString();
		}

		public String nextLine() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			StringBuilder res = new StringBuilder();
			do {
				res.appendCodePoint(c);
				c = read();
			} while (!isEndOfLine(c));
			return res.toString();
		}

		public boolean isSpaceChar(int c) {
			return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
		}

		private boolean isEndOfLine(int c) {
			return c == '\n' || c == '\r' || c == -1;
		}

	}
	static int prob(int x)
	{
	    if(x < 10)
	    return x;
	    else
	    {
	        if(x%10 == 0 || (x/10)% 10 == 0)
	        {
	            x /= 10;
	            return prob(x);
	            }
	            else
	            {
	    x = prob(x%10) * prob((x/10)% 10);
	    return prob(x);
	            }
	    }
	}
	



    public static void main(String[] args)
    {
        
        InputReader sc = new InputReader(System.in);
        PrintWriter w = new PrintWriter(System.out);
         int n = sc.ni();
        int m = sc.ni();
        int []arr = sc.nia(m);
        int t = 1;
        long res = 0;
        for(int i=0;i<m;i++)
        {
            if(arr[i] >= t)
            res += (long) arr[i]-t;
            else
            {
                res += (long) (n-t)+arr[i];
            }
            t = arr[i];
            
        }
        w.println(res);
       
        
        
        
          
       
       
      
       
        
        
        
           
        
       
           
           
        
        
        
    
        w.close();
        

        
    } 
    /*
    static boolean is(int p,int x,int y)
    {
        int flag = 0;
        
            for(int j=2;j<=p;j++)
            {
                if(x % j == 0)
                {
                    flag = 1;
                    break;
                }
                else 
                continue;
                
            }
            
        if(flag == 1)
        return false;
        else
        return true;
        
    }
    */
    static int binarysearch(int []arr,int p,int n)
    {
        
        int st = 0;
        int end = n-1;
        int mid = (st + end)/2;
        int temp = 0;
        while(st <= end)
        { 
            mid = (st + end)/2;
        
            if(p >= arr[mid])
            {
                st = mid+1;
                
            }
            else if(p < arr[mid])
            {
                end = mid-1;
                
            }
            temp = st;
            
            
        }
        
        return temp;
    }
    
   
    static class Student
    {
        int start;
        int end;
        int index;
        Student(int start,int end,int index)
        {
            this.start = start;
            this.end = end;
            this.index = index;
            
        }
        
    }
    static int lis(int arr[],int n)
    {
          int lis[] = new int[n];
          int i,j,max = 0;
 
          /* Initialize LIS values for all indexes */
           for ( i = 0; i < n; i++ )
              lis[i] = 1;
 
           /* Compute optimized LIS values in bottom up manner */
           for ( i = 1; i < n; i++ )
              for ( j = 0; j < i; j++ ) 
                         if ( arr[i] > arr[j] && lis[i] <= lis[j])
                    lis[i]++;
 
           /* Pick maximum of all LIS values */
           for ( i = 0; i < n; i++ )
              if ( max < lis[i] )
                 max = lis[i];
 
            return max;
    }
    
    
    public static int ip(String s){
		return Integer.parseInt(s);
	}
	
    
					 
}
