#include <bits/stdc++.h>
#include <cassert>
typedef long long int ll;
using namespace std;

// @@ !! LIM(f:updMaxMin debug)
// --> f:updMaxMin f:<< debug
// ---- inserted function updMaxMin from util.cc
template<typename T>
bool updMax(T& tmax, const T& x) {
  if (x > tmax) { tmax = x; return true;  }
  else          {           return false; }
}
template<typename T>
bool updMin(T& tmin, const T& x) {
  if (x < tmin) { tmin = x; return true;  }
  else          {           return false; }
}
// ---- end updMaxMin
// ---- inserted function << from util.cc
template <typename T1, typename T2>
ostream& operator<< (ostream& os, const pair<T1,T2>& p) {
  os << "(" << p.first << ", " << p.second << ")";
  return os;
}

template <typename T1, typename T2, typename T3>
ostream& operator<< (ostream& os, const tuple<T1,T2,T3>& t) {
  os << "(" << get<0>(t) << ", " << get<1>(t)
     << ", " << get<2>(t) << ")";
  return os;
}

template <typename T1, typename T2, typename T3, typename T4>
ostream& operator<< (ostream& os, const tuple<T1,T2,T3,T4>& t) {
  os << "(" << get<0>(t) << ", " << get<1>(t)
     << ", " << get<2>(t) << ", " << get<3>(t) << ")";
  return os;
}

template <typename T>
ostream& operator<< (ostream& os, const vector<T>& v) {
  os << '[';
  for (auto it = v.begin(); it != v.end(); it++) {
    if (it != v.begin()) os << ", ";
    os << *it;
  }
  os << ']';

  return os;
}

template <typename T, typename C>
ostream& operator<< (ostream& os, const set<T, C>& v) {
  os << '{';
  for (auto it = v.begin(); it != v.end(); it++) {
    if (it != v.begin()) os << ", ";
    os << *it;
  }
  os << '}';

  return os;
}

template <typename T, typename C>
ostream& operator<< (ostream& os, const unordered_set<T, C>& v) {
  os << '{';
  for (auto it = v.begin(); it != v.end(); it++) {
    if (it != v.begin()) os << ", ";
    os << *it;
  }
  os << '}';

  return os;
}

template <typename T, typename C>
ostream& operator<< (ostream& os, const multiset<T, C>& v) {
  os << '{';
  for (auto it = v.begin(); it != v.end(); it++) {
    if (it != v.begin()) os << ", ";
    os << *it;
  }
  os << '}';

  return os;
}

template <typename T1, typename T2, typename C>
ostream& operator<< (ostream& os, const map<T1, T2, C>& mp) {
  os << '[';
  for (auto it = mp.begin(); it != mp.end(); it++) {
    if (it != mp.begin()) os << ", ";
    os << it->first << ": " << it->second;
  }
  os << ']';

  return os;
}

template <typename T1, typename T2, typename C>
ostream& operator<< (ostream& os, const unordered_map<T1, T2, C>& mp) {
  os << '[';
  for (auto it = mp.begin(); it != mp.end(); it++) {
    if (it != mp.begin()) os << ", ";
    os << it->first << ": " << it->second;
  }
  os << ']';

  return os;
}

template <typename T, typename T2>
ostream& operator<< (ostream& os, const queue<T, T2>& orig) {
  queue<T, T2> que(orig);
  bool first = true;
  os << '[';
  while (!que.empty()) {
    T x = que.front(); que.pop();
    if (!first) os << ", ";
    os << x;
    first = false;
  }
  return os << ']';
}

template <typename T, typename T2, typename T3>
ostream& operator<< (ostream& os, const priority_queue<T, T2, T3>& orig) {
  priority_queue<T, T2, T3> pq(orig);
  bool first = true;
  os << '[';
  while (!pq.empty()) {
    T x = pq.top(); pq.pop();
    if (!first) os << ", ";
    os << x;
    first = false;
  }
  return os << ']';
}

template <typename T>
ostream& operator<< (ostream& os, const stack<T>& st) {
  stack<T> tmp(st);
  os << '[';
  bool first = true;
  while (!tmp.empty()) {
    T& t = tmp.top();
    if (first) first = false;
    else os << ", ";
    os << t;
    tmp.pop();
  }
  os << ']';
  return os;
}

#if __cplusplus >= 201703L
template <typename T>
ostream& operator<< (ostream& os, const optional<T>& t) {
  if (t.has_value()) os << "v(" << t.value() << ")";
  else               os << "nullopt";
  return os;
}
#endif

ostream& operator<< (ostream& os, int8_t x) {
  os << (int32_t)x;
  return os;
}

// ---- end <<
// ---- inserted library file debug.cc
template <class... Args>
string dbgFormat(const char* fmt, Args... args) {
  size_t len = snprintf(nullptr, 0, fmt, args...);
  char buf[len + 1];
  snprintf(buf, len + 1, fmt, args...);
  return string(buf);
}

template <class Head>
void dbgLog(Head&& head) {
  cerr << head << endl;
}

template <class Head, class... Tail>
void dbgLog(Head&& head, Tail&&... tail)
{
  cerr << head << " ";
  dbgLog(forward<Tail>(tail)...);
}

#if DEBUG
  #define DLOG(...)        dbgLog(__VA_ARGS__)
  #define DFMT(...)        cerr << dbgFormat(__VA_ARGS__) << endl
  #define DCALL(func, ...) func(__VA_ARGS__)
#else
  #define DLOG(...)
  #define DFMT(...)
  #define DCALL(func, ...)
#endif

#if DEBUG_LIB
  #define DLOG_LIB(...)        dbgLog(__VA_ARGS__)
  #define DFMT_LIB(...)        cerr << dbgFormat(__VA_ARGS__) << endl
  #define DCALL_LIB(func, ...) func(__VA_ARGS__)
#else
  #define DLOG_LIB(...)
  #define DFMT_LIB(...)
  #define DCALL_LIB(func, ...)
#endif

// ---- end debug.cc
// @@ !! LIM  -- end mark --

int main(/* int argc, char *argv[] */) {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  cout << setprecision(20);

  ll R, C, K; cin >> R >> C >> K;
  using sta = tuple<ll, ll, ll>;
  vector<sta> items;
  for (ll k = 0; k < K; k++) {
    ll r, c, v; cin >> r >> c >> v; r--; c--;
    items.emplace_back(r, c, v);
  }
  items.emplace_back(R+100, C+100, 0);
  sort(items.begin(), items.end());
  ll iidx = 0;
  vector cur(C + 1, vector(3, 0LL));
  ll itemR, itemC, itemV;
  tie(itemR, itemC, itemV) = items[0];
  for (ll r = 0; r <= R; r++) {
    vector nxt = vector(C + 1, vector(3, 0LL));
    for (ll c = 0; c < C; c++) {
      ll v = 0;
      if (r == itemR && c == itemC) {
	v = itemV;
	tie(itemR, itemC, itemV) = items[++iidx];
      }
      for (ll t = 0; t < 3; t++) {
	updMax(nxt[c][0], cur[c][t] + v);
	if (t+1 < 3) updMax(cur[c+1][t+1], cur[c][t] + v);
	updMax(cur[c+1][t], cur[c][t]);
      }
    }
    cur = move(nxt);
  }
  cout << cur[C-1][0] << endl;
  return 0;
}



Measured memory_bytes: 9472