#define LOCAL
#define _USE_MATH_DEFINES
#include <array>
#include <cassert>
#include <cstdio>
#include <cstring>
#include <iostream>
#include <iomanip>
#include <string>
#include <sstream>
#include <vector>
#include <queue>
#include <stack>
#include <list>
#include <set>
#include <map>
#include <unordered_set>
#include <unordered_map>
#include <algorithm>
#include <complex>
#include <cmath>
#include <numeric>
#include <bitset>
#include <functional>
#include <random>
#include <ctime>

using namespace std;

template <typename A, typename B>
ostream& operator <<(ostream& out, const pair<A, B>& a) {
  out << "(" << a.first << "," << a.second << ")";
  return out;
}
template <typename T, size_t N>
ostream& operator <<(ostream& out, const array<T, N>& a) {
  out << "["; bool first = true;
  for (auto& v : a) { out << (first ? "" : ", "); out << v; first = 0;} out << "]";
  return out;
}
template <typename T>
ostream& operator <<(ostream& out, const vector<T>& a) {
  out << "["; bool first = true;
  for (auto& v : a) { out << (first ? "" : ", "); out << v; first = 0;} out << "]";
  return out;
}
template <typename T, class Cmp>
ostream& operator <<(ostream& out, const set<T, Cmp>& a) {
  out << "{"; bool first = true;
  for (auto& v : a) { out << (first ? "" : ", "); out << v; first = 0;} out << "}";
  return out;
}
template <typename U, typename T, class Cmp>
ostream& operator <<(ostream& out, const map<U, T, Cmp>& a) {
  out << "{"; bool first = true;
  for (auto& p : a) { out << (first ? "" : ", "); out << p.first << ":" << p.second; first = 0;} out << "}";
  return out;
}
#ifdef LOCAL
#define trace(...) __f(#__VA_ARGS__, __VA_ARGS__)
#else
#define trace(...) 42
#endif
template <typename Arg1>
void __f(const char* name, Arg1&& arg1){
  cerr << name << ": " << arg1 << endl;
}
template <typename Arg1, typename... Args>
void __f(const char* names, Arg1&& arg1, Args&&... args){
  const char* comma = strchr(names + 1, ',');
  cerr.write(names, comma - names) << ": " << arg1 << " |";
  __f(comma + 1, args...);
}

typedef long long int64;
typedef pair<int, int> ii;
#define SZ(x) (int)((x).size())
const int INF = 1 << 29;
const int MOD = 1e9 + 7;
mt19937 mrand(random_device{}());
int rnd(int x) { return mrand() % x; }

struct fast_ios {
  fast_ios() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(10);
  };
} fast_ios_;

const int N = 3e3 + 10;
int c[N][N];
int64 dp[N][N][4];

void update(int64& x, int64 y) {
  x = max(x, y);
}

int main() {
  int n, m, len;
  cin >> n >> m >> len;
  for (int i = 0; i < len; ++i) {
    int x, y, z;
    cin >> x >> y >> z;
    --x; --y;
    c[x][y] = z;
  }
  for (int i = n - 1; i >= 0; --i) {
    for (int j = m - 1; j >= 0; --j) {
      for (int k = 3; k >= 0; --k) {
        if (i == n - 1 && j == m - 1) {
          dp[i][j][k] = c[i][j] && k != 3 ? c[i][j] : 0;
          continue;
        }
        if (i + 1 < n) {
          update(dp[i][j][k], dp[i + 1][j][0] + (k != 3 && c[i][j] ? c[i][j] : 0));
        }
        if (j + 1 < m) {
          if (k != 3 && c[i][j]) {
            update(dp[i][j][k], dp[i][j + 1][k + 1] + c[i][j]);
          }
          update(dp[i][j][k], dp[i][j + 1][k]);
        }
      }
    }
  }
  cout << dp[0][0][0] << endl;
  return 0;
}


Measured memory_bytes: 320624