import java.awt.Point;
import java.io.*;
import java.math.BigInteger;
import java.util.*;
import static java.lang.Math.*;

public class A1 implements Runnable{

    BufferedReader in;
    PrintWriter out;
    StringTokenizer tok = new StringTokenizer("");

    void init() throws FileNotFoundException{
        in = new BufferedReader(new FileReader("input.txt"));
        out = new PrintWriter("output.txt");
    }

    String readString() throws IOException{
        while(!tok.hasMoreTokens()){
            tok = new StringTokenizer(in.readLine());
        }
        return tok.nextToken();
    }

    int readInt() throws IOException{
        return Integer.parseInt(readString());
    }

    long readLong() throws IOException{
        return Long.parseLong(readString());
    }

    double readDouble() throws IOException{
        return Double.parseDouble(readString());
    }

    public static void main(String[] args){
        new Thread(null, new A1(), "", 256 * (1L << 20)).start();
    }

    public void run(){
        try{
            long t1 = System.currentTimeMillis();
            init();
            solve();
            out.close();
            long t2 = System.currentTimeMillis();
            System.err.println("Time = "+(t2-t1));
        }catch (Exception e){
            e.printStackTrace(System.err);
            System.exit(-1);
        }
    }

    class XY{

        long x, y;

        public XY(long x, long y) {
            this.x = x;
            this.y = y;
        }


    }

    long p;

    void solve() throws IOException{
        int n = readInt();
        p = readInt();
        long[] a = new long[n];
        for (int i = 0; i < n; i++){
            a[i] = readLong();
        }
        long[] f = new long[n];
        int[] pow = new int[n];
        pow[0] = pow[1] = 0;
        f[0] = f[1] = 1;
        for (int i = 2; i < n; i++){
            int x = i;
            pow[i] = pow[i-1];
            while (x % p == 0){
                x /= p;
                pow[i]++;
            }
            f[i] = f[i-1] * x % p;
        }
        long fn = f[n-1];
        long pn = pow[n-1];
        long s = 0;
        n--;
        for (int i = 0; i <= n; i++){
            if (pn == pow[i] + pow[n-i]){
                long d = fn * rev(f[i]) % p * rev(f[n-i]) % p * a[i] % p;
                if (((n - i) & 1) == 0){
                    s = (s + d) % p;
                }else{
                    s = (s - d + p) % p;
                }
            }
        }
        out.print(s);
    }

    long rev(long n){
        long x = xy(n, p).x;
        if (x <= 0){
            long k = -x / p + 1;
            x = p * k + x;
        }
        return x % p;
    }

    XY xy(long a, long b){
        if (a == 0){
            return new XY(0, 1);
        }
        XY xy = xy(b % a, a);
        return new XY(xy.y - b / a * xy.x, xy.x);
    }

}