#include <algorithm>
#include <array>
#include <cassert>
#include <climits>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <deque>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <vector>
using namespace std;
typedef long long ll;
#define REP(i,n) for(ll i = 0; i < (ll)(n); ++i)
#define FOR(i,a,b) for(ll i = (a); i < (ll)(b); ++i)
#define ALL(c) (c).begin(), (c).end()
#define SIZE(v) ((int)v.size())
template<class T> inline bool chmin(T& a, T b) {
    if (a > b) {
        a = b; return true;
    }
    return false;
}
template<class T> inline bool chmax(T& a, T b) {
    if (a < b) {
        a = b; return true;
    }
    return false;
}
template<int MOD> struct Fp {
    ll val;
    constexpr Fp(ll v = 0) noexcept : val(v % MOD) {
        if (val < 0) val += MOD;
    }
    constexpr int getmod() { return MOD; }
    constexpr Fp operator - () const noexcept {
        return val ? MOD - val : 0;
    }
    constexpr Fp operator + (const Fp& r) const noexcept { return Fp(*this) += r; }
    constexpr Fp operator - (const Fp& r) const noexcept { return Fp(*this) -= r; }
    constexpr Fp operator * (const Fp& r) const noexcept { return Fp(*this) *= r; }
    constexpr Fp operator / (const Fp& r) const noexcept { return Fp(*this) /= r; }
    constexpr Fp& operator += (const Fp& r) noexcept {
        val += r.val;
        if (val >= MOD) val -= MOD;
        return *this;
    }
    constexpr Fp& operator -= (const Fp& r) noexcept {
        val -= r.val;
        if (val < 0) val += MOD;
        return *this;
    }
    constexpr Fp& operator *= (const Fp& r) noexcept {
        val = val * r.val % MOD;
        return *this;
    }
    constexpr Fp& operator /= (const Fp& r) noexcept {
        ll a = r.val, b = MOD, u = 1, v = 0;
        while (b) {
            ll t = a / b;
            a -= t * b; swap(a, b);
            u -= t * v; swap(u, v);
        }
        val = val * u % MOD;
        if (val < 0) val += MOD;
        return *this;
    }
    constexpr bool operator == (const Fp& r) const noexcept {
        return this->val == r.val;
    }
    constexpr bool operator != (const Fp& r) const noexcept {
        return this->val != r.val;
    }
    friend constexpr ostream& operator << (ostream &os, const Fp<MOD>& x) noexcept {
        return os << x.val;
    }
    friend constexpr Fp<MOD> modpow(const Fp<MOD> &a, ll n) noexcept {
        if (n == 0) return 1;
        auto t = modpow(a, n / 2);
        t = t * t;
        if (n & 1) t = t * a;
        return t;
    }
};
constexpr ll MOD = 1e9 + 7;
using mint = Fp<MOD>;

#define pb push_back
#define mp make_pair
#define mt make_tuple

int main(void)
{
    ios::sync_with_stdio(false);
    cin.tie(0);

    int H, W, K;
    cin >> H >> W >> K;
    vector<vector<ll>> cells(H, vector<ll>(W));
    REP(k, K) {
        ll r, c, v;
        cin >> r >> c >> v;
        --r; --c;
        cells[r][c] = v;
    }

    vector<vector<array<ll, 4>>> dp(H + 1, vector<array<ll, 4>>(W + 1, array<ll, 4>()));
    

    REP(h, H) {
        REP(w, W) {
            // 右に移動 何もとらない
            REP(i, 4) {
                chmax(dp[h + 1][w + 1][i], dp[h + 1][w][i]);
            }
            // 下に移動 何もとらない
            REP(i, 4) {
                chmax(dp[h + 1][w + 1][0], dp[h][w + 1][i]);
            }

            // 右に移動  とる
            REP(i, 3) {
                chmax(dp[h + 1][w + 1][i + 1], dp[h + 1][w][i] + cells[h][w]);
            }

            // 下に移動  とる
            REP(i, 4) {
                chmax(dp[h + 1][w + 1][1], dp[h][w + 1][i] + cells[h][w]);
            }

            //REP(h, H + 1) {
            //    REP(w, W + 1) {
            //        cout << "(";
            //        REP(i, 4) {
            //            cout << dp[h][w][i] << " ";
            //        }
            //        cout << ")";
            //    }
            //    cout << endl;
            //}
            //cout << endl;
        }
    }

    ll ans = 0;
    REP(i, 4) {
        chmax(ans, dp[H][W][i]);
    }
    cout << ans << endl;
    

    return 0;
}


Measured memory_bytes: 355376