#include <iostream>
#include <cstdio>
#include <algorithm>
#include <bits/stdc++.h>
#define ALL(x) (x).begin(), (x).end()
#define sz(a) int(a.size())
#define rep(i,x,n) for(int i=x;i<n;i++)
#define repd(i,x,n) for(int i=x;i<=n;i++)
#define pii pair<int,int>
#define pll pair<long long ,long long>
#define gbtb ios::sync_with_stdio(false),cin.tie(0),cout.tie(0)
#define MS0(X) memset((X), 0, sizeof((X)))
#define MSC0(X) memset((X), '\0', sizeof((X)))
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define eps 1e-6
#define chu(x)  if(DEBUG_Switch) cout<<"["<<#x<<" "<<(x)<<"]"<<endl
#define du3(a,b,c) scanf("%d %d %d",&(a),&(b),&(c))
#define du2(a,b) scanf("%d %d",&(a),&(b))
#define du1(a) scanf("%d",&(a));
using namespace std;
typedef long long ll;
ll gcd(ll a, ll b) {return b ? gcd(b, a % b) : a;}
ll lcm(ll a, ll b) {return a / gcd(a, b) * b;}
ll powmod(ll a, ll b, ll MOD) { if (a == 0ll) {return 0ll;} a %= MOD; ll ans = 1; while (b) {if (b & 1) {ans = ans * a % MOD;} a = a * a % MOD; b >>= 1;} return ans;}
ll poww(ll a, ll b) { if (a == 0ll) {return 0ll;} ll ans = 1; while (b) {if (b & 1) {ans = ans * a ;} a = a * a ; b >>= 1;} return ans;}
void Pv(const vector<int> &V) {int Len = sz(V); for (int i = 0; i < Len; ++i) {printf("%d", V[i] ); if (i != Len - 1) {printf(" ");} else {printf("\n");}}}
void Pvl(const vector<ll> &V) {int Len = sz(V); for (int i = 0; i < Len; ++i) {printf("%lld", V[i] ); if (i != Len - 1) {printf(" ");} else {printf("\n");}}}
inline long long readll() {long long tmp = 0, fh = 1; char c = getchar(); while (c < '0' || c > '9') {if (c == '-') fh = -1; c = getchar();} while (c >= '0' && c <= '9') tmp = tmp * 10 + c - 48, c = getchar(); return tmp * fh;}
inline int readint() {int tmp = 0, fh = 1; char c = getchar(); while (c < '0' || c > '9') {if (c == '-') fh = -1; c = getchar();} while (c >= '0' && c <= '9') tmp = tmp * 10 + c - 48, c = getchar(); return tmp * fh;}
void pvarr_int(int *arr, int n, int strat = 1) {if (strat == 0) {n--;} repd(i, strat, n) {printf("%d%c", arr[i], i == n ? '\n' : ' ');}}
void pvarr_LL(ll *arr, int n, int strat = 1) {if (strat == 0) {n--;} repd(i, strat, n) {printf("%lld%c", arr[i], i == n ? '\n' : ' ');}}
const int maxn = 3010;
const int inf = 0x3f3f3f3f;
/*** TEMPLATE CODE * * STARTS HERE ***/
#define DEBUG_Switch 0
int n, m, k;
ll a[maxn][maxn];
ll dp[maxn][maxn][4];
int main()
{
#if DEBUG_Switch
    freopen("C:\\code\\input.txt", "r", stdin);
#endif
    //freopen("C:\\code\\output.txt","w",stdout);
    n = readint(); m = readint(); k = readint();
    repd(i, 1, k)
    {
        int x = readint(); int y = readint();
        ll w = readll();
        a[x][y] = w;
    }
//    repd(i, 1, n)
//    {
//        repd(j, 1, m)
//        {
//            printf("%lld ", a[i][j] );
//        }
//        printf("\n");
//    }
    repd(i, 1, n)
    {
        repd(j, 1, m)
        {
            if (i == 1)
            {
                if (j == 1)
                {
                    if (a[i][j] != 0)
                    {
                        dp[i][j][1] = a[i][j];
                    }
                } else
                {
                    if (a[i][j] != 0)
                    {
                        repd(k, 1, 3) {
                            dp[i][j][k] = max(dp[i][j - 1][k], dp[i][j - 1 ][k - 1] + a[i][j]);
                        }
                    }
                    repd(k, 0, 3) {
                        dp[i][j][k] = max(dp[i][j][k], dp[i][j - 1 ][k]);
                    }
                }
            } else if (j == 1)
            {
                if (a[i][j] != 0)
                {
                    repd(k, 0, 3) {
                        dp[i][j][1] = max(dp[i][j][1], dp[i - 1][j][k] + a[i][j]);
                    }
                }
                repd(k, 0, 3) {
                    dp[i][j][0] = max(dp[i][j][0], dp[i - 1][j][k]);
                }
            } else
            {
                if (a[i][j] != 0)
                {
                    repd(k, 0, 3) {
                        dp[i][j][1] = max(dp[i][j][1], dp[i - 1][j][k] + a[i][j]);
                    }
                }
                repd(k, 0, 3) {
                    dp[i][j][0] = max(dp[i][j][0], dp[i - 1][j][k]);
                }
                dp[i][j][0] = max(dp[i][j][0], dp[i][j - 1][0]);
                if (a[i][j] != 0)
                {
                    repd(k, 1, 3)
                    {
                        dp[i][j][k] = max(dp[i][j][k], dp[i][j - 1 ][k - 1] + a[i][j]);
                    }
                }
                repd(k, 0, 3) {
                    dp[i][j][k] = max(dp[i][j][k], dp[i][j - 1 ][k]);
                }
            }
        }
    }
//    repd(i, 1, n)
//    {
//        repd(j, 1, m)
//        {
//            printf("[%lld,%lld,%lld,%lld]  ", dp[i][j][0], dp[i][j][1], dp[i][j][2], dp[i][j][3]);
//        }
//        printf("\n");
//    }
    ll ans = 0ll;
    repd(i, 0, 3)
    {
        ans = max(ans, dp[n][m][i]);
    }
    printf("%lld\n", ans );
    return 0;
}




Measured memory_bytes: 356504