// #define _GLIBCXX_DEBUG
// #pragma GCC optimize ("trapv") // kills the program on integer overﬂows (but is really slow).
#include <bits/stdc++.h>
using namespace std;
using namespace std::chrono;

#define ll long long
#define ull unsigned long long
#define FIO ios_base::sync_with_stdio(false);cin.tie(NULL);
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define ff first
#define ss second
#define vt vector
#define vll vt<ll>
#define pll pair<ll,ll>
#define vpll vt<pll>
#define vvll vt<vll>
#define all(v) v.begin(),v.end()
#define FOR(i,n) for(ll i=0;i<n;i++)
#define ffo(i,a,b) for(ll i=a;i<=b;i++)
#define rfo(i,a,b) for(ll i=a;i>=b;i--)
#define space cout<<"\n\n";
#define endl "\n"
#define pqmx priority_queue<ll>
#define pqmn priority_queue<ll,vll,greater<ll>>
#define fps(x,y) fixed<<setprecision(y)<<x
#define merg(a,b,c) set_union(a.begin(),a.end(),b.begin(),b.end(),inserter(c,c.begin()))
#define set_ar(arr,v) memset(arr,v,sizeof(arr))
#define go_t int testcases; cin>>testcases; ffo(caseno,1,testcases)

#define ctime auto start = high_resolution_clock::now()
#define etime auto stop = high_resolution_clock::now()
#define ptime auto z1z = duration_cast<microseconds>(stop-start); cout<<"Time elapsed : "<<z1z.count()<<" microseconds\n"

#define dbg1(x)             cout <<#x<<": "<<x<<'\n';
#define dbg2(x, y)          cout <<#x<<": "<<x<<" | "<<#y<<": "<<y<<'\n';
#define dbg3(x, y, z)       cout <<#x<<": "<<x<<" | "<<#y<<": "<<y<<" | "<<#z<<": "<<z<<'\n';
#define dbg4(a, b, c, d)    cout <<#a<<": "<<a<<" | "<<#b<<": "<<b<<" | "<<#c<<": "<<c<<" | "<<#d<<": "<<d<<'\n';
#define dbg5(a, b, c, d, e) cout <<#a<<": "<<a<<" | "<<#b<<": "<<b<<" | "<<#c<<": "<<c<<" | "<<#d<<": "<<d<<" | "<<#e<<": "<<e<<'\n';

const ll mod = 1e9 + 7;
const ll N = 5e3 + 6;
const ll maxN = 2e5 + 5;
const ll MAX_SIZE = 2e6 + 6;
const ll INF = 0x3f3f3f3f3f3f3f3fll;
const double PI = 3.14159265359;

ll powerM(ll x, ll y, ll M = mod) { // default argument
	ll v = 1; x = x % M; while (y > 0) {if (y & 1)v = (v * x) % M; y = y >> 1; x = (x * x) % M;} return v;
}

ll power(ll x, ll y) {
	ll v = 1; while (y > 0) {if (y & 1)v = v * x; y = y >> 1; x = x * x;} return v;
}

ll r, c, k;
ll mat[3003][3003];
ll dp[3003][3003][4];

// ll dp(ll x, ll y, ll amt) {
// 	if (x == r + 1 || y == c + 1) {
// 		return 0;
// 	}
// 	ll& ans = cache[amt][y][x];
// 	if (ans != -1)
// 		return ans;
// 	ans = 0;
// 	// either we pick the element or we don't and after that we move down or left
// 	// amt represents the maximum amount of numbers that we can choose
// 	if (mat[x][y] == 0) {
// 		for (int i = amt; i >= 0; --i) {
// 			ans = max({ans, (cache[i][y][x + 1] == -1 ? dp(x + 1, y, i) : cache[i][y][x + 1]), (cache[i][y + 1][x] == -1 ? dp(x, y + 1, i) : cache[i][y + 1][x])});
// 		}
// 	}
// 	else if (amt == 0) {
// 		for (int i = min(3ll, c - y + 1); i >= 0; --i) {
// 			ans = max(ans, (cache[i][y][x + 1] == -1 ? dp(x + 1, y, i) : cache[i][y][x + 1]) );
// 		}
// 	}
// 	else {
// 		ans = max({ans, mat[x][y] + (cache[amt - 1][y + 1][x] == -1 ? dp(x, y + 1, amt - 1) : cache[amt - 1][y + 1][x]) , (cache[amt][y + 1][x] == -1 ? dp(x, y + 1, amt) : cache[amt][y + 1][x]) });
// 		for (int i = min(3ll, c - y + 1); i >= 0; --i) {
// 			ans = max({ans, mat[x][y] + (cache[i][y][x + 1] == -1 ? dp(x + 1, y, i) : cache[i][y][x + 1])});
// 		}
// 	}
// 	return ans;
// }

int main()
{
#ifndef ONLINE_JUDGE
	freopen("in4.txt", "r", stdin);
	freopen("out3.txt", "w", stdout);
#endif
	FIO
	cin >> r >> c >> k;
	FOR(i, k) {
		ll x, y, z;
		cin >> x >> y >> z;
		mat[x][y] = z;
	}
	// converting top down to bottom up
	for (int i = r; i >= 1; i--) {
		for (int j = c; j >= 1; j--) {
			for (int amt = 1; amt <= 3; amt++) {
				dp[i][j][amt] = max({dp[i][j][amt], dp[i][j][amt - 1], dp[i][j + 1][amt], mat[i][j] + dp[i][j + 1][amt - 1], mat[i][j] + dp[i + 1][j][3]});
			}
		}
	}
	ll ans = 0;
	for (int i = 1; i <= 3; i++) {
		ans = max(ans, dp[1][1][i]);
	}
	cout << ans;
	return 0;
}


Measured memory_bytes: 355440