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.math.*;
import java.util.*;
 
 
 
 
 
public class B {
 
    static MyScanner in = new MyScanner();
    static   PrintWriter out = new PrintWriter(new OutputStreamWriter(System.out));
    static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    static StringTokenizer st;
    static long H,W;
    static BitSet bs;
    static long mod = 1000000007;
      // All possible moves of a knight 
    static   int X[] = { 2, 1, -1, -2, -2, -1, 1, 2 }; 
    static int Y[] = { 1, 2, 2, 1, -1, -2, -2, -1 }; 
    public static void main(String args[]) throws IOException {
    /**
1.What is the unknown:
2.What are the data: it takes t minutes to bake k carrot cakes
he needs n cakes,
3.What is the condition: d minutes build the oven
4.What is the restriction: min amount of times the second cakes must do
5. understand the problem:
6. What are the cases edges in the problem:
*/
        int n= in.nextInt();
        int positon = 0;
        int m= in.nextInt();
        long sum =0;
        for(int i=0;i<m;i++){
            int k = in.nextInt();
            if(positon<=k){
                sum+=(k-positon);
                positon = k;
            }else{
                sum+=(n-positon+k);
                positon = k;
            }
        }
        out.println(sum-1);
        out.flush();
    } 
    static int modInverse(int a, int m) 
    { 
        int m0 = m; 
        int y = 0, x = 1; 
  
        if (m == 1) 
            return 0; 
  
        while (a > 1) 
        { 
            // q is quotient 
            int q = a / m; 
  
            int t = m; 
  
            // m is remainder now, process 
            // same as Euclid's algo 
            m = a % m; 
            a = t; 
            t = y; 
  
            // Update x and y 
            y = x - q * y; 
            x = t; 
        } 
  
        // Make x positive 
        if (x < 0) 
            x += m0; 
  
        return x; 
    } 
    static boolean isVowel(char c){
        if(c=='a'||c=='e'||c=='i'||c=='o'||c=='u'||c=='y'){
            return true;
        }
        return false ;
    }
    static class IP implements Comparable<IP>{
        public int first,second;
        IP(int first, int second){
            this.first = first;
            this.second = second;
        }
        public int compareTo(IP ip){
            if(first==ip.first)
                return second-ip.second;
            return first-ip.first;    
        }
 
    }
        
       static long gcd(long a, long b){
        return b!=0?gcd(b, a%b):a;
    }
 
        static boolean isEven(long a) {
            return (a&1)==0;
        }
    
    public static class MyScanner {
        BufferedReader br;
        StringTokenizer st;
   
        public MyScanner() {
           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;
        }
  
     }
}