import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.io.BufferedWriter;
import java.io.Writer;
import java.io.OutputStreamWriter;
import java.util.InputMismatchException;
import java.io.IOException;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author gaidash
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        OutputWriter out = new OutputWriter(outputStream);
        B2SnukesColoring2ABCEdit solver = new B2SnukesColoring2ABCEdit();
        solver.solve(1, in, out);
        out.close();
    }

    static class B2SnukesColoring2ABCEdit {
        private int[][] color;

        private void paint(int fromI, int toI, int fromJ, int toJ) {
            for (int i = fromI; i < toI; i++) {
                for (int j = fromJ; j < toJ; j++) {
                    color[i][j] = 0;
                }
            }
        }

        public void solve(int testNumber, InputReader in, OutputWriter out) {
            int sizeJ = in.nextInt();
            int sizeI = in.nextInt();
            int n = in.nextInt();
            color = new int[sizeI][sizeJ];
            for (int[] row : color) {
                Arrays.fill(row, 1);
            }
            for (int rep = 0; rep < n; rep++) {
                int j = in.nextInt();
                int i = in.nextInt();
                int type = in.nextInt();
                if (type == 1) {
                    paint(0, sizeI, 0, j);
                } else if (type == 2) {
                    paint(0, sizeI, j, sizeJ);
                } else if (type == 3) {
                    paint(0, i, 0, sizeJ);
                } else {
                    paint(i, sizeI, 0, sizeJ);
                }
            }

            int ret = 0;
            for (int i = 0; i < sizeI; i++) {
                for (int j = 0; j < sizeJ; j++) {
                    ret += color[i][j];
                }
            }

            out.println(ret);
        }

    }

    static class OutputWriter {
        private final PrintWriter writer;

        public OutputWriter(OutputStream outputStream) {
            writer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(outputStream)));
        }

        public OutputWriter(Writer writer) {
            this.writer = new PrintWriter(writer);
        }

        public void close() {
            writer.close();
        }

        public void println(int i) {
            writer.println(i);
        }

    }

    static class InputReader {
        private InputStream stream;
        private byte[] buf = new byte[1024];
        private int curChar;
        private int numChars;
        private InputReader.SpaceCharFilter filter;

        public InputReader(InputStream stream) {
            this.stream = stream;
        }

        public int read() {
            if (numChars == -1) {
                throw new InputMismatchException();
            }
            if (curChar >= numChars) {
                curChar = 0;
                try {
                    numChars = stream.read(buf);
                } catch (IOException e) {
                    throw new InputMismatchException();
                }
                if (numChars <= 0) {
                    return -1;
                }
            }
            return buf[curChar++];
        }

        public int nextInt() {
            int c = read();
            while (isSpaceChar(c)) {
                c = read();
            }
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            int res = 0;
            do {
                if (c < '0' || c > '9') {
                    throw new InputMismatchException();
                }
                res *= 10;
                res += c - '0';
                c = read();
            } while (!isSpaceChar(c));
            return res * sgn;
        }

        public boolean isSpaceChar(int c) {
            if (filter != null) {
                return filter.isSpaceChar(c);
            }
            return isWhitespace(c);
        }

        public static boolean isWhitespace(int c) {
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

        public interface SpaceCharFilter {
            public boolean isSpaceChar(int ch);

        }

    }
}



Measured memory_bytes: 23636