// template version 1.12
using namespace std;
#include <iostream>
#include <bits/stdc++.h>

// varibable settings
#define infile "../test/sample-1.in"
#define int long long //{{{
const int INF=1e18;
const int MOD=1e9+7; //}}}

// define basic macro {{{
#define _overload3(_1,_2,_3,name,...) name
#define _rep(i,n) repi(i,0,n)
#define repi(i,a,b) for(int i=(int)(a);i<(int)(b);++i)
#define rep(...) _overload3(__VA_ARGS__,repi,_rep,)(__VA_ARGS__)
#define _rrep(i,n) rrepi(i,0,n)
#define rrepi(i,a,b) for(int i=(int)((b)-1);i>=(int)(a);--i)
#define rrep(...) _overload3(__VA_ARGS__,rrepi,_rrep,)(__VA_ARGS__)
#define each(i,a) for (auto&& i : a)
#define all(x) (x).begin(),(x).end()
#define sz(x) ((int)(x).size())
#define pb(a) push_back(a)
#define mp(a, b) make_pair(a, b)
#define uni(x) sort(all(x));x.erase(unique(all(x)),x.end())
#define ub upper_bound
#define lb lower_bound
#define posl(A, x) (lower_bound(all(A), x)-A.begin())
#define posu(A, x) (upper_bound(all(A),x)-A.begin())
template<class T> inline void chmax(T &a, const T &b) { if((a) < (b)) (a) = (b); }
template<class T> inline void chmin(T &a, const T &b) { if((a) > (b)) (a) = (b); }

typedef long long ll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef long double ld;
typedef pair<int,int> pii;
typedef tuple<int,int,int> iii;

template<typename T> using PQ = priority_queue<T, vector<T>, greater<T>>;
struct Fast { Fast(){ std::cin.tie(0); ios::sync_with_stdio(false); } } fast;

#if defined(PCM) || defined(LOCAL)
  #include "lib/dump.hpp"
#else
  #define dump(...) 42
  #define dump_1d(...) 42
  #define dump_2d(...) 42
#endif
//}}}

// 隣接リストで使う辺を表す型
struct Edge {
  int to, cost;  // 辺の接続先頂点, 辺の重み
  Edge(int to, int cost) : to(to), cost(cost) {}  // コンストラクタ
};

typedef vector<vector<Edge> > AdjList;  // 隣接リストの型
AdjList graph;  // グラフの辺を格納した構造体
                // graph[v][i]は頂点vから出るi番目の辺Edge

vector<int> dist; // 最短距離

int solve(){
    
    int H=3001;
    int W=3001;
    //int H=10;
    //int W=10;
    ll a,b,x;
    ll h,w,k;cin>>h>>w>>k;
    ll ans=0;
    
    vector<vector<ll>> v(H, vector<int>(W));
    rep(i,k){
        cin>>a>>b>>x;
        v[a][b]=x;
    }
    vector<vector<vector<ll>>> dp(H, vector<vector<ll>>(W, vector<ll>(4)));
    repi(i,1,h+1){
        repi(j,1,w+1){
            
            ll up_max=0;
            rep(x,4){
                if(up_max<dp[i-1][j][x])up_max=dp[i-1][j][x];
            }
            dp[i][j][0]=up_max;
            
            if(v[i][j]!=0 && dp[i][j][1]<up_max+v[i][j])dp[i][j][1]=up_max+v[i][j];
                
            if (dp[i][j][0]<dp[i][j-1][0])dp[i][j][0]=dp[i][j-1][0];
            repi(x,1,4){
                if (dp[i][j][x]<dp[i][j-1][x])dp[i][j][x]=dp[i][j-1][x];
                if (dp[i][j][x]<dp[i][j-1][x-1]+v[i][j])dp[i][j][x]=dp[i][j-1][x-1]+v[i][j];
            }
/*                dp[i][j][x]=max(dp[i][j][x],dp[i][j-1][x],dp[i][j-1][x-1]+v[i][j]);
            }
            
            for x in range(1,4)[::-1]:
                dp[i][j][x]=max(dp[i][j][x],dp[i][j-1][x],dp[i][j-1][x-1]+v[i][j])
            
*/
        }
    }
    
    
    
    rep(x,4){
        if (ans<dp[h][w][x])ans=dp[h][w][x];
    }

    
    
    cout<<ans<<endl;
    
    return 0;
}

signed main() { //{{{
#ifdef INPUT_FROM_FILE
  std::ifstream in(infile);
  std::cin.rdbuf(in.rdbuf());
#endif
  solve();
  return 0;
} //}}}


### FIXED CODE ###

import sys,bisect,string,math,time,functools,random,fractions
from heapq import heappush,heappop,heapify
from collections import deque,defaultdict,Counter
from itertools import permutations,combinations,groupby
rep=range;R=range
def Golf():n,*t=map(int,open(0).read().split())
def I():return int(input())
def S_():return input()
def IS():return input().split()
def LS():return [i for i in input().split()]
def MI():return map(int,input().split())
def LI():return [int(i) for i in input().split()]
def LI_():return [int(i)-1 for i in input().split()]
def NI(n):return [int(input()) for i in range(n)]
def NI_(n):return [int(input())-1 for i in range(n)]
def StoLI():return [ord(i)-97 for i in input()]
def ItoS(n):return chr(n+97)
def LtoS(ls):return ''.join([chr(i+97) for i in ls])
def RA():return map(int,open(0).read().split())
def RLI(n=8,a=1,b=10):return [random.randint(a,b)for i in range(n)]
def RI(a=1,b=10):return random.randint(a,b)
def Rtest(T):
    case,err=0,0
    for i in range(T):
        inp=INP()
        a1,ls=naive(*inp)
        a2=solve(*inp)
        if a1!=a2:
            print((a1,a2),inp)
            err+=1
        case+=1
    print('Tested',case,'case with',err,'errors')
def GI(V,E,ls=None,Directed=False,index=1):
    org_inp=[];g=[[] for i in range(V)]
    FromStdin=True if ls==None else False
    for i in range(E):
        if FromStdin:
            inp=LI()
            org_inp.append(inp)
        else:
            inp=ls[i]
        if len(inp)==2:
            a,b=inp;c=1
        else:
            a,b,c=inp
        if index==1:a-=1;b-=1
        aa=(a,c);bb=(b,c);g[a].append(bb)
        if not Directed:g[b].append(aa)
    return g,org_inp
def GGI(h,w,search=None,replacement_of_found='.',mp_def={'#':1,'.':0},boundary=1):
    #h,w,g,sg=GGI(h,w,search=['S','G'],replacement_of_found='.',mp_def={'#':1,'.':0},boundary=1) # sample usage
    mp=[boundary]*(w+2);found={}
    for i in R(h):
        s=input()
        for char in search:
            if char in s:
                found[char]=((i+1)*(w+2)+s.index(char)+1)
                mp_def[char]=mp_def[replacement_of_found]
        mp+=[boundary]+[mp_def[j] for j in s]+[boundary]
    mp+=[boundary]*(w+2)
    return h+2,w+2,mp,found
def TI(n):return GI(n,n-1)
def accum(ls):
    rt=[0]
    for i in ls:rt+=[rt[-1]+i]
    return rt
def bit_combination(n,base=2):
    rt=[]
    for tb in R(base**n):s=[tb//(base**bt)%base for bt in R(n)];rt+=[s]
    return rt
def gcd(x,y):
    if y==0:return x
    if x%y==0:return y
    while x%y!=0:x,y=y,x%y
    return y
def YN(x):print(['NO','YES'][x])
def Yn(x):print(['No','Yes'][x])
def show(*inp,end='\n'):
    if show_flg:print(*inp,end=end)

mo=10**9+7
inf=float('inf')
FourNb=[(-1,0),(1,0),(0,1),(0,-1)];EightNb=[(-1,0),(1,0),(0,1),(0,-1),(1,1),(-1,-1),(1,-1),(-1,1)];compas=dict(zip('WENS',FourNb));cursol=dict(zip('LRUD',FourNb))
l_alp=string.ascii_lowercase
#sys.setrecursionlimit(10**9)
read=sys.stdin.buffer.read;readline=sys.stdin.buffer.readline;input=lambda:sys.stdin.readline().rstrip()


show_flg=False
show_flg=True

ans=0

h,w,k=LI()
v=[[0]*(w+1) for i in range(h+1)]
for i in rep(k):
    a,b,x=LI()
    v[a][b]=x

dp=[[[0]*(w+1) for i in range(h+1)] for i in range(4)]

for i in range(1,h+1):
    for j in range(1,w+1):
        up_max=max(dp[x][i-1][j]for x in range(4))
        dp[0][i][j]=up_max
        if v[i][j]!=0:
            dp[1][i][j]=max(dp[1][i][j],up_max+v[i][j])
        dp[0][i][j]=max(dp[0][i][j],dp[0][i][j-1])
        for x in range(1,4)[::-1]:
            dp[x][i][j]=max(dp[x][i][j],dp[x][i][j-1],dp[x-1][i][j-1]+v[i][j])
            

ans=max([dp[x][h][w]for x in range(4)])
print(ans)