import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.InputMismatchException;
import java.util.List;
import java.util.Map;
import java.util.PriorityQueue;

public class Main {

	private static final String NO = "NO";
	private static final String YES = "YES";
	InputStream is;
	PrintWriter out;
	String INPUT = "";

	private static final long MOD = 1000000007;
	private static final int INF = Integer.MAX_VALUE;

	void solve() {
		int T = 1;
		for (int i = 0; i < T; i++)
			solve(i);
	}

	int n;

	Map<String, Long> v = new HashMap<String, Long>();

	static class Item implements Comparable<Item> {
		public Item(String l, String r, long c) {
			left = l;
			right = r;
			cost = c;
		}

		String left;
		String right;
		long cost;

		public boolean isPalindrome() {
			String s = left + right;
			for (int i = 0; i < s.length() / 2; i++)
				if (s.charAt(i) != s.charAt(s.length() - 1 - i))
					return false;
			return true;
		}

		public Item add(String s, long c) {
			if (right.length() == 0 & can(left, s)) {
				int l = Math.min(left.length(), s.length());
				return new Item(left.substring(l), s.substring(0, s.length() - l), cost + c);
			} else if (left.length() == 0 & can(s, right)) {
				int l = Math.min(right.length(), s.length());
				return new Item(s.substring(l), right.substring(0, right.length() - l), cost + c);
			}
			return null;
		}

		static boolean can(String l, String r) {
			int min = Math.min(l.length(), r.length());
			for (int i = 0; i < min; i++) {
				if (l.charAt(i) != r.charAt(r.length() - 1 - i))
					return false;
			}
			return true;
		}

		@Override
		public int compareTo(Item o) {
			return Long.signum(cost - o.cost);
		}

		public String toString() {
			return left + " " + right + " " + cost;
		}
	}

	void solve(int T) {
		n = ni();
		int m = ni();
		int K = ni();
		int a[][] = new int[n][m];
		long dp[][][] = new long[n + 1][m + 1][4];
		for (int i = 0; i < K; i++) {
			int r = ni() - 1;
			int c = ni() - 1;
			int v = ni();
			a[r][c] = v;
		}
//		tr(a);
		for (int r = 0; r < n; r++) {
			for (int c = 0; c < m; c++) {
				for (int kk = 1; kk < 4; kk++) {
					dp[r + 1][c + 1][kk] = Math.max(dp[r][c + 1][3] + a[r][c],
							Math.max(dp[r + 1][c][kk], dp[r + 1][c][kk - 1] + a[r][c]));
				}
			}
		}
		out.print(dp[n][m][3]);
	}

	// a^b
	long power(long a, long b) {
		long x = 1, y = a;
		while (b > 0) {
			if (b % 2 != 0) {
				x = (x * y) % MOD;
			}
			y = (y * y) % MOD;
			b /= 2;
		}
		return x % MOD;
	}

	private long gcd(long a, long b) {
		while (a != 0) {
			long tmp = b % a;
			b = a;
			a = tmp;
		}
		return b;
	}

	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");
	}

	public static void main(String[] args) throws Exception {
		new Main().run();
	}

	private byte[] inbuf = new byte[1024];
	public int lenbuf = 0, ptrbuf = 0;
	private boolean vis[];

	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) {
			if (!(isSpaceChar(b)))
				buf[p++] = (char) b;
			b = readByte();
		}
		return n == p ? buf : Arrays.copyOf(buf, p);
	}

	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[] na(int n) {
		int[] a = new int[n];
		for (int i = 0; i < n; i++)
			a[i] = ni();
		return a;
	}

	private List<Integer> na2(int n) {
		List<Integer> a = new ArrayList<Integer>();
		for (int i = 0; i < n; i++)
			a.add(ni());
		return a;
	}

	private int[][] na(int n, int m) {
		int[][] a = new int[n][];
		for (int i = 0; i < n; i++)
			a[i] = na(m);
		return a;
	}

	private int ni() {
		int num = 0, 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 long[] nl(int n) {
		long[] a = new long[n];
		for (int i = 0; i < n; i++)
			a[i] = nl();
		return a;
	}

	private long[][] nl(int n, int m) {
		long[][] a = new long[n][];
		for (int i = 0; i < n; i++)
			a[i] = nl(m);
		return a;
	}

	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));
	}

}

Measured memory_bytes: 590104