package contest190726;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.InputMismatchException;

public class E {
	InputStream is;
	PrintWriter out;
	String INPUT = "";
	
	void solve()
	{
		int H = ni(), W = ni(), n = ni();
		int[][] co = new int[n][];
		for(int i = 0;i < n;i++) {
			co[i] = new int[] {ni(), ni(), ni()};
		}
		
		// (0,H+1) 2 (W+1,H+1)
		// 1           3
		// (0,0) 0 (W+1,0)
		
		int[][] xs = new int[4][];
		{
			int[] lxs = new int[n];
			int p = 0;
			for(int i = 0;i < n;i++) {
				if(co[i][1] == 0) {
					lxs[p++] = co[i][0];
				}
			}
			lxs = Arrays.copyOf(lxs, p);
			Arrays.sort(lxs);
			xs[0] = uniq(lxs);
		}
		{
			int[] lxs = new int[n];
			int p = 0;
			for(int i = 0;i < n;i++) {
				if(co[i][1] == H+1) {
					lxs[p++] = W+1-co[i][0];
				}
			}
			lxs = Arrays.copyOf(lxs, p);
			Arrays.sort(lxs);
			xs[2] = uniq(lxs);
		}
		{
			int[] lxs = new int[n];
			int p = 0;
			for(int i = 0;i < n;i++) {
				if(co[i][0] == 0) {
					lxs[p++] = H+1-co[i][1];
				}
			}
			lxs = Arrays.copyOf(lxs, p);
			Arrays.sort(lxs);
			xs[1] = uniq(lxs);
		}
		{
			int[] lxs = new int[n];
			int p = 0;
			for(int i = 0;i < n;i++) {
				if(co[i][0] == W+1) {
					lxs[p++] = co[i][1];
				}
			}
			lxs = Arrays.copyOf(lxs, p);
			Arrays.sort(lxs);
			xs[3] = uniq(lxs);
		}
		
		SegmentTreeRMQ[] st = new SegmentTreeRMQ[4];
		for(int i = 0;i < 4;i++) {
			st[i] = new SegmentTreeRMQ(n+1);
		}
		
		long ans = 0;
		for(int[] c : co) {
			int type = 0;
			int x = 0;
			if(c[1] == 0) {
				type = 0;
				x = c[0];
			}else if(c[0] == 0) {
				type = 1;
				x = H+1-c[1];
			}else if(c[1] == H+1) {
				type = 2;
				x = W+1-c[0];
			}else {
				type = 3;
				x = c[1];
			}
			int indx = Arrays.binarySearch(xs[type], x);
			int or = -st[type].minx(indx, indx+1);
			int y = or + c[2];
			int U = type % 2 == 0 ? W+1 : H+1;
			int V = type % 2 == 1 ? W+1 : H+1;
			
			int dir = -1;
			int minlen = V;
			{
				// 左と衝突
				int last = st[type+1&3].lastle(n-1, -x);
				if(last != -1) {
					int len = V-xs[type+1&3][last];
					if(len < minlen) {
						minlen = len;
						dir = 1;
					}
				}
			}
			
			{
				// 正面衝突
				int ind = Arrays.binarySearch(xs[type+2&3], U-x);
				if(ind >= 0) {
					int len = V-(-st[type+2&3].minx(ind, ind+1));
					if(len < minlen) {
						minlen = len;
						dir = 2;
					}
				}
			}
			{
				// 右と衝突
				int first = st[type+3&3].firstle(0, -(U-x));
				if(first != -1) {
					int len = xs[type+3&3][first];
					if(len < minlen) {
						minlen = len;
						dir = 3;
					}
				}
			}
			
//			tr(minlen, y, dir);
			if(minlen <= y) {
				// 衝突
				st[type].update(indx, 0);
				ans -= or;
				if(dir == -1) {
				}else if(dir == 2) {
					int ind = Arrays.binarySearch(xs[type+2&3], U-x);
					ans -= -st[type+2&3].minx(ind, ind+1);
					st[type+2&3].update(ind, 0);
				}else if(dir == 1) {
					int last = st[type+1&3].lastle(n-1, -x);
					ans -= -st[type+1&3].minx(last, last+1);
					st[type+1&3].update(last, 0);
				}else if(dir == 3) {
					int first = st[type+3&3].firstle(0, -(U-x));
					ans -= -st[type+3&3].minx(first, first+1);
					st[type+3&3].update(first, 0);
				}
			}else {
				st[type].update(Arrays.binarySearch(xs[type], x), -y);
				ans += c[2];
			}
		}
		out.println(ans);
	}
	
	public static class SegmentTreeRMQ {
		public int M, H, N;
		public int[] st;
		
		public SegmentTreeRMQ(int n)
		{
			N = n;
			M = Integer.highestOneBit(Math.max(N-1, 1))<<2;
			H = M>>>1;
			st = new int[M];
//			Arrays.fill(st, 0, M, Integer.MAX_VALUE);
		}
		
		public SegmentTreeRMQ(int[] a)
		{
			N = a.length;
			M = Integer.highestOneBit(Math.max(N-1, 1))<<2;
			H = M>>>1;
			st = new int[M];
			for(int i = 0;i < N;i++){
				st[H+i] = a[i];
			}
			Arrays.fill(st, H+N, M, Integer.MAX_VALUE);
			for(int i = H-1;i >= 1;i--)propagate(i);
		}
		
		public void update(int pos, int x)
		{
			st[H+pos] = x;
			for(int i = (H+pos)>>>1;i >= 1;i >>>= 1)propagate(i);
		}
		
		private void propagate(int i)
		{
			st[i] = Math.min(st[2*i], st[2*i+1]);
		}
		
		public int minx(int l, int r){
			int min = Integer.MAX_VALUE;
			if(l >= r)return min;
			while(l != 0){
				int f = l&-l;
				if(l+f > r)break;
				int v = st[(H+l)/f];
				if(v < min)min = v;
				l += f;
			}
			
			while(l < r){
				int f = r&-r;
				int v = st[(H+r)/f-1];
				if(v < min)min = v;
				r -= f;
			}
			return min;
		}
		
		public int min(int l, int r){ return l >= r ? 0 : min(l, r, 0, H, 1);}
		
		private int min(int l, int r, int cl, int cr, int cur)
		{
			if(l <= cl && cr <= r){
				return st[cur];
			}else{
				int mid = cl+cr>>>1;
				int ret = Integer.MAX_VALUE;
				if(cl < r && l < mid){
					ret = Math.min(ret, min(l, r, cl, mid, 2*cur));
				}
				if(mid < r && l < cr){
					ret = Math.min(ret, min(l, r, mid, cr, 2*cur+1));
				}
				return ret;
			}
		}
		
		public int firstle(int l, int v) {
			int cur = H+l;
			while(true){
				if(st[cur] <= v){
					if(cur < H){
						cur = 2*cur;
					}else{
						return cur-H;
					}
				}else{
					cur++;
					if((cur&cur-1) == 0)return -1;
					if((cur&1)==0)cur>>>=1;
				}
			}
		}
		
		public int lastle(int l, int v) {
			int cur = H+l;
			while(true){
				if(st[cur] <= v){
					if(cur < H){
						cur = 2*cur+1;
					}else{
						return cur-H;
					}
				}else{
					if((cur&cur-1) == 0)return -1;
					cur--;
					if((cur&1)==1)cur>>>=1;
				}
			}
		}
	}

	
	public static int[] uniq(int[] a)
	{
		int n = a.length;
		int p = 0;
		for(int i = 0;i < n;i++) {
			if(i == 0 || a[i] != a[i-1])a[p++] = a[i];
		}
		return Arrays.copyOf(a, p);
	}

	
	
	
	
	
	void run() throws Exception
	{
		is = INPUT.isEmpty() ? System.in : new ByteArrayInputStream(INPUT.getBytes());
		out = new PrintWriter(System.out);
		
		long s = System.currentTimeMillis();
		solve();
		out.flush();
		if(!INPUT.isEmpty())tr(System.currentTimeMillis()-s+"ms");
//		Thread t = new Thread(null, null, "~", Runtime.getRuntime().maxMemory()){
//			@Override
//			public void run() {
//				long s = System.currentTimeMillis();
//				solve();
//				out.flush();
//				if(!INPUT.isEmpty())tr(System.currentTimeMillis()-s+"ms");
//			}
//		};
//		t.start();
//		t.join();
	}
	
	public static void main(String[] args) throws Exception { new E().run(); }
	
	private byte[] inbuf = new byte[1024];
	public int lenbuf = 0, ptrbuf = 0;
	
	private int readByte()
	{
		if(lenbuf == -1)throw new InputMismatchException();
		if(ptrbuf >= lenbuf){
			ptrbuf = 0;
			try { lenbuf = is.read(inbuf); } catch (IOException e) { throw new InputMismatchException(); }
			if(lenbuf <= 0)return -1;
		}
		return inbuf[ptrbuf++];
	}
	
	private boolean isSpaceChar(int c) { return !(c >= 33 && c <= 126); }
	private int skip() { int b; while((b = readByte()) != -1 && isSpaceChar(b)); return b; }
	
	private double nd() { return Double.parseDouble(ns()); }
	private char nc() { return (char)skip(); }
	
	private String ns()
	{
		int b = skip();
		StringBuilder sb = new StringBuilder();
		while(!(isSpaceChar(b))){ // when nextLine, (isSpaceChar(b) && b != ' ')
			sb.appendCodePoint(b);
			b = readByte();
		}
		return sb.toString();
	}
	
	private char[] ns(int n)
	{
		char[] buf = new char[n];
		int b = skip(), p = 0;
		while(p < n && !(isSpaceChar(b))){
			buf[p++] = (char)b;
			b = readByte();
		}
		return n == p ? buf : Arrays.copyOf(buf, p);
	}
	
	private int[] na(int n)
	{
		int[] a = new int[n];
		for(int i = 0;i < n;i++)a[i] = ni();
		return a;
	}
	
	private long[] nal(int n)
	{
		long[] a = new long[n];
		for(int i = 0;i < n;i++)a[i] = nl();
		return a;
	}
	
	private char[][] nm(int n, int m) {
		char[][] map = new char[n][];
		for(int i = 0;i < n;i++)map[i] = ns(m);
		return map;
	}
	
	private int[][] nmi(int n, int m) {
		int[][] map = new int[n][];
		for(int i = 0;i < n;i++)map[i] = na(m);
		return map;
	}
	
	private int ni() { return (int)nl(); }
	
	private long nl()
	{
		long num = 0;
		int b;
		boolean minus = false;
		while((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'));
		if(b == '-'){
			minus = true;
			b = readByte();
		}
		
		while(true){
			if(b >= '0' && b <= '9'){
				num = num * 10 + (b - '0');
			}else{
				return minus ? -num : num;
			}
			b = readByte();
		}
	}
	
	private static void tr(Object... o) { System.out.println(Arrays.deepToString(o)); }
}