import java.io.*;

import java.util.*;

public class barn1 {

public static int boarddist(int x,int y) {

return Math.max(y-x, x-y);// Difference

//TODO add offset if needed

}

public static int count(int[] arr) {

boolean b=false;int c=0;int temp;

for(int i=0;i<arr.length;i++) {

temp=arr[i];

if(temp==0 && b) {

b=false;

c++;

}

if(temp==1 && b==false) {

b=true;

}

}

return c;

}

public static void main(String[] args) throws IOException{

/*

*Variable names and what they means

* bs prefix means blocked stall

* x,y,z are really just M S C in the problem

* bstalls is a array of blocked stalls

* stalls is a Bit representation of all stalls

* WARNING "blockedstalls" is a multi use temporary variable that is reused many times for memory efficency.

*/

BufferedReader f=new BufferedReader(new FileReader("barn1.in"));

StringTokenizer st=new StringTokenizer(f.readLine());

int x=Integer.parseInt(st.nextToken());//Read x

int y=Integer.parseInt(st.nextToken());//Read y

int z=Integer.parseInt(st.nextToken());//Read z

int[] stalls=new int[y+1];// Offset a bit

int blockedstall=-1;

int[] bstalls=new int[z+1];//Offset a bit

for(int i=0;i<z;i++) {

blockedstall=Integer.parseInt(f.readLine());

stalls[blockedstall]=1;

bstalls[i]=blockedstall;

}

f.close();

f=null;

for(int i:stalls) {System.out.print(i+" ");}

int combination=0;

int[][][] mergecosts=new int[y+1][(2*z*(z-1))+1][2];//int[Offset][Which combination][x,y]

for(int i=0;i<mergecosts.length;i++) {

for(int j=0;j<mergecosts[i].length;j++) {

mergecosts[i][j][0]=-1; // Doubles check speed if first is -1 then skip

}

}

for(int bs1:bstalls) {

for(int bs2:bstalls) {

if(bs1==bs2 || bs1>bs2 || bs1==0 || bs2==0) {

//System.out.println("Debug point 2: Info, blockedstall: "+blockedstall+", combination: "+combination+", More info: bs1: "+bs1+", bs2: "+bs2);

System.out.println("Both are same, bs1: "+bs1+", bs2: "+bs2);

continue;

}else {

combination++;//increment

blockedstall=boarddist(bs1,bs2);

//System.out.println("Debug point 1: Info, blockedstall: "+blockedstall+", combination: "+combination+", More info: bs1: "+bs1+", bs2: "+bs2);

System.out.println("bs1: "+bs1+", bs2: "+bs2);

mergecosts[blockedstall][combination][0]=bs1;

mergecosts[blockedstall][combination][1]=bs2;

}

}

}

System.out.println(combination);

combination=0;

//for(int i=0;i<)

}

}