import java.math.BigInteger;
import java.util.Scanner;

public class navigation2 {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int R = in.nextInt();
        int C = in.nextInt();
        int N = in.nextInt();
        BigInteger start = BigInteger.valueOf(1);
        BigInteger currentCell = start;
        BigInteger[][] matrix = new BigInteger[R][C];
        for (int row = R - 1; row >= 0 ; row--) {
            for (int col = 0; col < C; col++) {
                matrix[row][col] = currentCell;
                currentCell = currentCell.multiply(BigInteger.valueOf(2));
//                System.out.printf("%d ",matrix[row][col]);
            }
//            System.out.println();
            start = start.multiply(BigInteger.valueOf(2));
            currentCell = start;
        }
        int coef = Math.max(R, C);
        BigInteger sum = BigInteger.ONE;
        int currentRow = R - 1;
        int currentCol = 0;
        boolean[][] wasHere = new boolean[R][C];
        wasHere[currentRow][currentCol] = true;
        in.nextLine();
        String[] codes = in.nextLine().split(" ");
        for (int moves = 0; moves < codes.length ; moves++) {
            int codeRow = Integer.parseInt(codes[moves]) / coef;
            int codeCol = Integer.parseInt(codes[moves]) % coef;
            if (currentCol < codeCol) {
                for (int i = currentCol; i < codeCol; i++) {
                    currentCol++;
                    if (wasHere[currentRow][currentCol] == false) {
                        sum = sum.add(matrix[currentRow][currentCol]);
                        wasHere[currentRow][currentCol] = true;
                    }
                }
            } else {
                for (int i = currentCol; i > codeCol; i--) {
                    currentCol--;
                    if (wasHere[currentRow][currentCol] == false) {
                        sum = sum.add(matrix[currentRow][currentCol]);
                        wasHere[currentRow][currentCol] = true;
                    }
                }
            }
            if (currentRow < codeRow) {
                for (int i = currentRow; i < codeRow; i++) {
                    currentRow++;
                    if (wasHere[currentRow][currentCol] == false) {
                        sum = sum.add(matrix[currentRow][currentCol]);
                        wasHere[currentRow][currentCol] = true;
                    }
                }
            } else {
                for (int i = currentRow; i > codeRow; i--) {
                    currentRow--;
                    if (wasHere[currentRow][currentCol] == false) {
                        sum = sum.add(matrix[currentRow][currentCol]);
                        wasHere[currentRow][currentCol] = true;
                    }
                }
            }
        }
        System.out.println(sum);
    }
}