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.IOException;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.StringTokenizer;


public class Main {
	public static void main(String[] args) throws IOException{
    		Reader.init(System.in);
    		int n=Reader.nextInt();
    		int m=Reader.nextInt();
    		int currenthouse=1;
    		int h;
    		long count=0;
    		for(int i=0;i<m;i++){
    			h=Reader.nextInt();
    			if(h<currenthouse){
    				count+=n-currenthouse+h;
    			}
    			else
    			{
    				if(h>currenthouse){
    					count+=h-currenthouse;
    					
    				}
    				
    			}
    			currenthouse=h;
    		}
    		System.out.println(count);
    		
    		
	}
	
        static class Reader {
            static BufferedReader reader;
            static StringTokenizer tokenizer;

            /** call this method to initialize reader for InputStream */
            static void init(InputStream input) {
                reader = new BufferedReader(
                             new InputStreamReader(input) );
                tokenizer = new StringTokenizer("");
            }

            /** get next word */
            static String next() throws IOException {
                while ( ! tokenizer.hasMoreTokens() ) {
                    //TODO add check for eof if necessary
                    tokenizer = new StringTokenizer(
                           reader.readLine() );
                }
                return tokenizer.nextToken();
            }
            
            /** get next line */
            static String nextLine() {
              String line="";
			try {
				line = reader.readLine();
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
              return  line;
            }

            static int nextInt() throws IOException {
                return Integer.parseInt( next() );
            }
            
            static long nextLong() throws IOException {
                return Long.parseLong( next() );
            }
            
            static double nextDouble() throws IOException {
                return Double.parseDouble( next() );
            }
        }
    

}

