#ifndef __MINMAX_H__
#define __MINMAX_H__

/* updated: 2020-08-02 */

#include <algorithm>
#include <functional>

/* 
// 最小値と最大値をビット演算の演算子オーバーロードで表記できるようにするクラス
// 演算子 | が max, 演算子 & が min を表す
// (扱うときは暗黙の型変換とオーバーロード解決に注意)
*/
template <class T, class Pred = std::less<T>>
class MinMax {
	T value_m = T();

public:
	MinMax() = default;
	MinMax(const T& value);
	MinMax(const MinMax<T, Pred>& other) = default;

	MinMax<T, Pred>& operator=(const T& value);
	MinMax<T, Pred>& operator=(const MinMax<T, Pred>& other) = default;

	MinMax<T, Pred>& operator|=(const T& other);
	MinMax<T, Pred>& operator&=(const T& other);

	operator T() const;
};

template <class T, class Pred>
MinMax<T, Pred> operator|(const MinMax<T, Pred>& a, const MinMax<T, Pred>& b);
template <class T, class Pred>
MinMax<T, Pred> operator&(const MinMax<T, Pred>& a, const MinMax<T, Pred>& b);
template <class T, class Pred, class U>
MinMax<T, Pred> operator|(const MinMax<T, Pred>& a, const U& b);
template <class T, class Pred, class U>
MinMax<T, Pred> operator&(const MinMax<T, Pred>& a, const U& b);
template <class T, class Pred, class U>
MinMax<T, Pred> operator|(const U& a, const MinMax<T, Pred>& b);
template <class T, class Pred, class U>
MinMax<T, Pred> operator&(const U& a, const MinMax<T, Pred>& b);

template<class T, class Pred>
MinMax<T, Pred>::MinMax(const T& value)
	: value_m(value) {
}

template<class T, class Pred>
MinMax<T, Pred>& MinMax<T, Pred>::operator=(const T& value) {
	value_m = value;
	return *this;
}

template<class T, class Pred>
MinMax<T, Pred>& MinMax<T, Pred>::operator|=(const T& other) {
	value_m = std::max(value_m, other, Pred());
	return *this;
}

template<class T, class Pred>
MinMax<T, Pred>& MinMax<T, Pred>::operator&=(const T& other) {
	value_m = std::min(value_m, other, Pred());
	return *this;
}

template<class T, class Pred>
MinMax<T, Pred>::operator T() const {
	return value_m;
}

template<class T, class Pred>
MinMax<T, Pred> operator|(const MinMax<T, Pred>& a, const MinMax<T, Pred>& b) {
	MinMax<T, Pred> ret(a);
	ret |= b;
	return ret;
}

template<class T, class Pred>
MinMax<T, Pred> operator&(const MinMax<T, Pred>& a, const MinMax<T, Pred>& b) {
	MinMax<T, Pred> ret(a);
	ret &= b;
	return ret;
}

template<class T, class Pred, class U>
MinMax<T, Pred> operator|(const MinMax<T, Pred>& a, const U& b) {
	return a | MinMax<T, Pred>(b);
}

template<class T, class Pred, class U>
MinMax<T, Pred> operator&(const MinMax<T, Pred>& a, const U& b) {
	return a & MinMax<T, Pred>(b);
}

template<class T, class Pred, class U>
MinMax<T, Pred> operator|(const U& a, const MinMax<T, Pred>& b) {
	return MinMax<T, Pred>(a) | b;
}

template<class T, class Pred, class U>
MinMax<T, Pred> operator&(const U& a, const MinMax<T, Pred>& b) {
	return MinMax<T, Pred>(a) & b;
}

using MMInt = MinMax<int>;
using MMLL = MinMax<long long int>;
using MMDouble = MinMax<double>;

#endif
#define _CRT_SECURE_NO_WARNINGS
#define _SCL_SECURE_NO_WARNINGS
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cassert>
#include <iostream>
#include <string>
#include <vector>
#include <list>
#include <utility>
#include <algorithm>
#include <functional>
#include <cmath>
#include <stack>
#include <queue>
#include <set>
#include <map>
#include <iomanip>
#include <sstream>
#include <bitset>
#include <limits>
#include <numeric>
#include <valarray>
#include <fstream>
#include <array>
#include <random>
#include <unordered_set>
#include <unordered_map>

using namespace std;
using uint = uint32_t;
using LL = int64_t;
using ULL = uint64_t;
using PP = pair<LL, LL>;
template <typename T> using PriorityQ = priority_queue<T, vector<T>, greater<T> >;
#define REP(i, a, n) for(LL i = (a), i##_max_ = (n); i < i##_max_; ++i)
#define REM(i, a, n) for(LL i = (LL)(n) - 1, i##_min_ = (a); i >= i##_min_; --i)
#define FLOAT fixed << setprecision(16)
#define SPEEDUP { cin.tie(NULL); ios::sync_with_stdio(false); }
const int INF = 0x3FFFFFFF;
const LL INFLL = 0x3FFFFFFF3FFFFFFF;
const double INFD = 1.0e+308;
const double EPS = 1.0e-9;

void YesNo(bool b) { cout << (b ? "Yes" : "No") << endl; }
void YESNO(bool b) { cout << (b ? "YES" : "NO") << endl; }
template <class T, class U> istream& operator>>(istream& ist, pair<T, U>& right) { return ist >> right.first >> right.second; }
template <class T, class U> ostream& operator<<(ostream& ost, const pair<T, U>& right) { return ost << right.first << ' ' << right.second; }
template <class T, class TCompatible, size_t N> void Fill(T(&dest)[N], const TCompatible& val) { fill(dest, dest + N, val); }
template <class T, class TCompatible, size_t M, size_t N> void Fill(T(&dest)[M][N], const TCompatible& val) { for (int i = 0; i < M; ++i) Fill(dest[i], val); }
template <class T> T Next() { T buf; cin >> buf; return buf; }
istream& Ignore(istream& ist) { string s; ist >> s; return ist; }
bool Inside(int i, int j, int h, int w) { return i >= 0 && i < h&& j >= 0 && j < w; }

#ifdef ONLY_MY_ENVIR
#include "Accumulator.h"
#include "Algebraic.h"
#include "BinaryMatrix.h"
#include "BinaryTree.h"
#include "Bipartite.h"
#include "BIT.h"
#include "Compressor.h"
#include "Decompositions.h"
#include "DiscreteLog.h"
#include "DynamicMod.h"
#include "Exponential.h"
#include "Factorization.h"
#include "FFT.h"
#include "FlowSolver.h"
#include "Geometric2D.h"
#include "Geometric2DFloat.h"
#include "Geometric3D.h"
#include "Geometric3DFloat.h"
#include "Graph.h"
#include "GraphUtil.h"
#include "Interpolation.h"
#include "IntMod.h"
#include "KDTree.h"
#include "LazySegmentTree.h"
#include "LIS.h"
#include "List.h"
#include "Math.h"
#include "MathUtil.h"
#include "Matrix.h"
#include "MinCostFlowSolver.h"
#include "MinMax.h"
#include "Numbers.h"
#include "Optimize.h"
#include "Permutation.h"
#include "Polynomial.h"
#include "Position.h"
#include "Random.h"
#include "Range.h"
#include "Rational.h"
#include "RollingHash.h"
#include "RuntimeMod.h"
#include "SegmentTree.h"
#include "SegmentTree2D.h"
#include "Sets.h"
#include "Shortest.h"
#include "SlidingWindow.h"
#include "SpanningTree.h"
#include "StringSearching.h"
#include "SuffixArray.h"
#include "SwitchList.h"
#include "Timer.h"
#include "Tree.h"
#include "TreeUtil.h"
#include "UnionFind.h"
#include "Util.h"
#include "VectorUtil.h"
#endif

#ifdef __GNUC__
typedef __int128 LLL;
istream& operator>>(istream& ist, __int128& val) { LL tmp; ist >> tmp; val = tmp; return ist; }
ostream& operator<<(ostream& ost, __int128 val) { LL tmp = val; ost << tmp; return ost; }
#endif

int h, w, k;
int f[3000][3000];

MMLL dp[4][3000][3000];
int main() {
	cin >> h >> w >> k;

	REP(i, 0, k) {
		int a, b, c;
		cin >> a >> b >> c;
		--a; --b;
		f[a][b] = c;
	}

	Fill(dp, -INFLL);
	dp[0][0][0] = 0;

	REP(i, 0, h) {
		REP(j, 0, w) {
			REM(c, 0, 3) {
				dp[c + 1][i][j] |= dp[c][i][j] + f[i][j];
			}

			REM(c, 0, 3 + 1) {
				if (i < h - 1) dp[0][i + 1][j] |= dp[c][i][j];
				if (j < w - 1) dp[c][i][j + 1] |= dp[c][i][j];
			}
		}
	}

	MMLL mx = 0;
	REP(c, 0, 3 + 1) {
		mx |= dp[c][h - 1][w - 1];
	}
	cout << mx << endl;
	return 0;
}


Measured memory_bytes: 319984