#include "bits/stdc++.h"
// Begin Header {{{
#define all(x) (x).begin(), (x).end()
#define rep(i, s, n) for (i64 i = (s), i##_limit = (n); i < i##_limit; ++i)
#define repr(i, s, t) for (i64 i = (s), i##_limit = (t); i >= i##_limit; --i)
#define repc(i, s, t) for (i64 i = (s), i##_limit = (t); i <= i##_limit; ++i)
#define var(type, ...) \
    type __VA_ARGS__;  \
    read(__VA_ARGS__);
#ifndef DBG
#define dump(...)
#endif
using namespace std;
using i64 = int_fast64_t;
using pii = pair<i64, i64>;
template <class T, class U>
inline bool chmax(T &a, const U &b) {
    return b > a && (a = b, true);
}
template <class T, class U>
inline bool chmin(T &a, const U &b) {
    return b < a && (a = b, true);
}
constexpr int INF = 0x3f3f3f3f;
constexpr i64 LINF = 0x3f3f3f3f3f3f3f3fLL;

template <class T>
inline vector<T> makeV(const T &initValue, size_t sz) {
    return vector<T>(sz, initValue);
}

template <class T, class... Args>
inline auto makeV(const T &initValue, size_t sz, Args... args) {
    return vector<decltype(makeV<T>(initValue, args...))>(
        sz, makeV<T>(initValue, args...));
}

template <class T>
inline istream &operator>>(istream &is, vector<T> &vec) {
    for (auto &e : vec) is >> e;
    return is;
}

inline void read() {}

template <class Head, class... Tail>
inline void read(Head &head, Tail &... tail) {
    cin >> head;
    read(tail...);
}

inline void print() { cout << "\n"; }

template <class Head, class... Tail>
inline void print(Head &&head, Tail &&... tail) {
    cout << head;
    if (sizeof...(tail)) cout << ' ';
    print(forward<Tail>(tail)...);
}

template <class T>
inline ostream &operator<<(ostream &os, const vector<T> &vec) {
    static constexpr const char *delim[] = {" ", ""};
    for (const auto &e : vec) os << e << delim[&e == &vec.back()];
    return os;
}

template <class Container>
struct Rev {
    Container &x_;
    inline Rev(Container &x) : x_(x) {}
    inline auto begin() { return rbegin(x_); }
    inline auto end() { return rend(x_); }
};
// }}} End Header

template <typename Func>
struct FixPoint : Func {
    inline constexpr FixPoint(Func &&f) noexcept : Func(forward<Func>(f)) {}

    template <typename... Args>
    inline decltype(auto) operator()(Args &&... args) const {
        return Func::operator()(*this, forward<Args>(args)...);
    }
};

template <typename Func>
inline decltype(auto) makeFixPoint(Func &&f) {
    return FixPoint<Func>{forward<Func>(f)};
}

signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.setf(ios_base::fixed);
    cout.precision(12);

    var(int, H, W, N);
    auto vs = makeV<int>(0, H + 1, W + 1);

    rep(i, 0, N) {
        var(int, y, x, v);
        vs[y][x] = v;
    }

    auto dp = makeV<i64>(-1, H + 1, W + 1, 4);

    const i64 ans = makeFixPoint([&](auto rec, int y, int x, int cnt) -> i64 {
        if (y > H || x > W) return 0;
        auto &res = dp[y][x][cnt];
        if (~res) return res;

        res = 0;
        chmax(res, rec(y + 1, x, 0));
        chmax(res, rec(y, x + 1, cnt));
        if (vs[y][x] && cnt < 3) {
            chmax(res, rec(y + 1, x, 0) + vs[y][x]);
            chmax(res, rec(y, x + 1, cnt + 1) + vs[y][x]);
        }

        return res;
    })(1, 1, 0);

    print(ans);

    return 0;
}


Measured memory_bytes: 672688