import java.io.IOException; import java.util.InputMismatchException; import java.util.TreeSet; public class Main { void run() { MyScanner sc = new MyScanner(); int w = sc.nextInt(); int h = sc.nextInt(); int n = sc.nextInt(); TreeSet wset = new TreeSet(); TreeSet hset = new TreeSet(); for (int i = 0; i < n; i++) { int a = sc.nextInt(); int b = sc.nextInt(); wset.add(a); hset.add(b); } int wc = wset.size(); int hc = hset.size(); long sum = wc * h + hc * w - wc * hc - n; System.out.println(sum); } public static void main(String[] args) { new Main().run(); } public void mapDebug(int[][] a) { System.out.println("--------map display---------"); for (int i = 0; i < a.length; i++) { for (int j = 0; j < a[i].length; j++) { System.out.printf("%3d ", a[i][j]); } System.out.println(); } System.out.println("----------------------------" + '\n'); } class MyScanner { int read() { try { return System.in.read(); } catch (IOException e) { throw new InputMismatchException(); } } boolean isSpaceChar(int c) { return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1; } boolean isEndline(int c) { return c == '\n' || c == '\r' || c == -1; } int nextInt() { return Integer.parseInt(next()); } int[] nextIntArray(int n) { int[] array = new int[n]; for (int i = 0; i < n; i++) array[i] = nextInt(); return array; } long nextLong() { return Long.parseLong(next()); } long[] nextLongArray(int n) { long[] array = new long[n]; for (int i = 0; i < n; i++) array[i] = nextLong(); return array; } double nextDouble() { return Double.parseDouble(next()); } double[] nextDoubleArray(int n) { double[] array = new double[n]; for (int i = 0; i < n; i++) array[i] = nextDouble(); return array; } String next() { int c = read(); while (isSpaceChar(c)) c = read(); StringBuilder res = new StringBuilder(); do { res.appendCodePoint(c); c = read(); } while (!isSpaceChar(c)); return res.toString(); } String[] nextStringArray(int n) { String[] array = new String[n]; for (int i = 0; i < n; i++) array[i] = next(); return array; } String nextLine() { int c = read(); while (isEndline(c)) c = read(); StringBuilder res = new StringBuilder(); do { res.appendCodePoint(c); c = read(); } while (!isEndline(c)); return res.toString(); } } }