#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#include<iostream>
#include<string>
#include<cstdio>
#include<vector>
#include<cmath>
#include<algorithm>
#include<functional>
#include<iomanip>
#include<queue>
#include<ciso646>
#include<random>
#include<map>
#include<set>
#include<bitset>
#include<stack>
#include<unordered_map>
#include<unordered_set>
#include<utility>
#include<cassert>
#include<complex>
#include<numeric>
#include<array>
#include<chrono>
using namespace std;

//#define int long long
typedef long long ll;

typedef unsigned long long ul;
typedef unsigned int ui;
//ll mod = 1;
//constexpr ll mod = 998244353;
constexpr ll mod = 1000000007;
const int mod17 = 1000000007;
const ll INF = mod * mod;
typedef pair<int, int>P;

#define rep(i,n) for(int i=0;i<n;i++)
#define per(i,n) for(int i=n-1;i>=0;i--)
#define Rep(i,sta,n) for(int i=sta;i<n;i++)
#define rep1(i,n) for(int i=1;i<=n;i++)
#define per1(i,n) for(int i=n;i>=1;i--)
#define Rep1(i,sta,n) for(int i=sta;i<=n;i++)
#define all(v) (v).begin(),(v).end()
typedef pair<ll, ll> LP;

using ld = long double;
typedef pair<ld, ld> LDP;
const ld eps = 1e-10;
const ld pi = acosl(-1.0);

template<typename T>
void chmin(T& a, T b) {
	a = min(a, b);
}
template<typename T>
void chmax(T& a, T b) {
	a = max(a, b);
}
template<typename T>
vector<T> vmerge(vector<T>& a, vector<T>& b) {
	vector<T> res;
	int ida = 0, idb = 0;
	while (ida < a.size() || idb < b.size()) {
		if (idb == b.size()) {
			res.push_back(a[ida]); ida++;
		}
		else if (ida == a.size()) {
			res.push_back(b[idb]); idb++;
		}
		else {
			if (a[ida] < b[idb]) {
				res.push_back(a[ida]); ida++;
			}
			else {
				res.push_back(b[idb]); idb++;
			}
		}
	}
	return res;
}
template<typename T>
void cinarray(vector<T>& v) {
	rep(i, v.size())cin >> v[i];
}
template<typename T>
void coutarray(vector<T>& v) {
	rep(i, v.size()) {
		if (i > 0)cout << " "; cout << v[i];
	}
	cout << "\n";
}
ll mod_pow(ll x, ll n, ll m = mod) {
	if (n < 0) {
		ll res = mod_pow(x, -n, m);
		return mod_pow(res, m - 2, m);
	}
	if (abs(x) >= m)x %= m;
	if (x < 0)x += m;
	//if (x == 0)return 0;
	ll res = 1;
	while (n) {
		if (n & 1)res = res * x % m;
		x = x * x % m; n >>= 1;
	}
	return res;
}
//mod should be <2^31
struct modint {
	int n;
	modint() :n(0) { ; }
	modint(ll m) {
		if (m < 0 || mod <= m) {
			m %= mod; if (m < 0)m += mod;
		}
		n = m;
	}
	operator int() { return n; }
};
bool operator==(modint a, modint b) { return a.n == b.n; }
bool operator<(modint a, modint b) { return a.n < b.n; }
modint operator+=(modint& a, modint b) { a.n += b.n; if (a.n >= mod)a.n -= (int)mod; return a; }
modint operator-=(modint& a, modint b) { a.n -= b.n; if (a.n < 0)a.n += (int)mod; return a; }
modint operator*=(modint& a, modint b) { a.n = ((ll)a.n * b.n) % mod; return a; }
modint operator+(modint a, modint b) { return a += b; }
modint operator-(modint a, modint b) { return a -= b; }
modint operator*(modint a, modint b) { return a *= b; }
modint operator^(modint a, ll n) {
	if (n == 0)return modint(1);
	modint res = (a * a) ^ (n / 2);
	if (n % 2)res = res * a;
	return res;
}

ll inv(ll a, ll p) {
	return (a == 1 ? 1 : (1 - p * inv(p % a, a)) / a + p);
}
modint operator/(modint a, modint b) { return a * modint(inv(b, mod)); }
modint operator/=(modint& a, modint b) { a = a / b; return a; }
const int max_n = 1 << 20;
modint fact[max_n], factinv[max_n];
void init_f() {
	fact[0] = modint(1);
	for (int i = 0; i < max_n - 1; i++) {
		fact[i + 1] = fact[i] * modint(i + 1);
	}
	factinv[max_n - 1] = modint(1) / fact[max_n - 1];
	for (int i = max_n - 2; i >= 0; i--) {
		factinv[i] = factinv[i + 1] * modint(i + 1);
	}
}
modint comb(int a, int b) {
	if (a < 0 || b < 0 || a < b)return 0;
	return fact[a] * factinv[b] * factinv[a - b];
}
modint combP(int a, int b) {
	if (a < 0 || b < 0 || a < b)return 0;
	return fact[a] * factinv[a - b];
}

ll gcd(ll a, ll b) {
	a = abs(a); b = abs(b);
	if (a < b)swap(a, b);
	while (b) {
		ll r = a % b; a = b; b = r;
	}
	return a;
}
template<typename T>
void addv(vector<T>& v, int loc, T val) {
	if (loc >= v.size())v.resize(loc + 1, 0);
	v[loc] += val;
}
/*const int mn = 2000005;
bool isp[mn];
vector<int> ps;
void init() {
	fill(isp + 2, isp + mn, true);
	for (int i = 2; i < mn; i++) {
		if (!isp[i])continue;
		ps.push_back(i);
		for (int j = 2 * i; j < mn; j += i) {
			isp[j] = false;
		}
	}
}*/

//[,val)
template<typename T>
auto prev_itr(set<T>& st, T val) {
	auto res = st.lower_bound(val);
	if (res == st.begin())return st.end();
	res--; return res;
}

//[val,)
template<typename T>
auto next_itr(set<T>& st, T val) {
	auto res = st.lower_bound(val);
	return res;
}
using mP = pair<modint, modint>;
mP operator+(mP a, mP b) {
	return { a.first + b.first,a.second + b.second };
}
mP operator+=(mP& a, mP b) {
	a = a + b; return a;
}
mP operator-(mP a, mP b) {
	return { a.first - b.first,a.second - b.second };
}
mP operator-=(mP& a, mP b) {
	a = a - b; return a;
}
LP operator+(LP a, LP b) {
	return { a.first + b.first,a.second + b.second };
}
LP operator+=(LP& a, LP b) {
	a = a + b; return a;
}
LP operator-(LP a, LP b) {
	return { a.first - b.first,a.second - b.second };
}
LP operator-=(LP& a, LP b) {
	a = a - b; return a;
}

mt19937 mt(time(0));

const string drul = "DRUL";
string senw = "SENW";
//DRUL,or SENW
//int dx[4] = { 1,0,-1,0 };
//int dy[4] = { 0,1,0,-1 };

//-----------------------------------------

template<typename T>
struct SegT {
private:
	int sz; vector<T> node;
	T init_c;
	function<T(T, T)> f;
public:
	void init(int n, T _init_c, function<T(T, T)> _f) {
		init_c = _init_c; f = _f;
		sz = 1;
		while (sz < n)sz *= 2;
		node.resize(2 * sz - 1, init_c);
	}
	void update(int k, T a) {
		k += sz - 1;
		node[k] = a;
		while (k > 0) {
			k = (k - 1) / 2;
			node[k] = f(node[k * 2 + 1], node[k * 2 + 2]);
		}
	}
	T query(int a, int b, int k = 0, int l = 0, int r = -1) {
		if (r < 0)r = sz;
		if (r <= a || b <= l)return init_c;
		else if (a <= l && r <= b)return node[k];
		else {
			T vl = query(a, b, k * 2 + 1, l, (l + r) / 2);
			T vr = query(a, b, k * 2 + 2, (l + r) / 2, r);
			return f(vl, vr);
		}
	}
	int searchri(int le, T x, function<bool(T, T)> comp) {
		int  k = le + sz - 1;
		if (comp(x, node[k]))return le;
		//x = f(x, node[k]);
		while (k > 0) {
			int mem = k;
			k = (k - 1) / 2;
			if (2 * k + 1 == mem) {
				if (comp(x, node[2 * k + 2])) {
					k = 2 * k + 2; break;
				}
				//x = f(x, node[2 * k + 2]);
			}
		}
		if (k == 0)return sz;
		while (k < sz - 1) {
			if (comp(x, node[2 * k + 1])) {
				k = 2 * k + 1;
			}
			else {
				//x = f(x, node[2 * k + 1]);
				k = 2 * k + 2;
			}
		}
		return k - (sz - 1);
	}
	int searchle(int le, T x, function<bool(T, T)> comp) {
		int  k = le + sz - 1;
		if (comp(x, node[k]))return le;
		//x = f(x, node[k]);
		while (k > 0) {
			int mem = k;
			k = (k - 1) / 2;
			if (2 * k + 2 == mem) {
				if (comp(x, node[2 * k + 1])) {
					k = 2 * k + 1; break;
				}
				//x = f(x, node[2 * k + 1]);
			}
		}
		if (k == 0)return -1;
		while (k < sz - 1) {
			if (comp(x, node[2 * k + 2])) {
				k = 2 * k + 2;
			}
			else {
				//x = f(x, node[2 * k + 2]);
				k = 2 * k + 1;
			}
		}
		return k - (sz - 1);
	}
};

void solve(){
	int h, w, n; cin >> w >> h >> n;
	vector<int> x(n), y(n), l(n);
	vector<int> vx, vy;
	vx.push_back(0); vx.push_back(h - 1);
	vy.push_back(0); vy.push_back(w - 1);
	
	rep(i, n) {
		cin >> x[i] >> y[i] >> l[i]; x[i]--; y[i]--;
		vx.push_back(x[i]);
		vy.push_back(y[i]);
	}
	sort(all(vx)); vx.erase(unique(all(vx)), vx.end());
	sort(all(vy)); vy.erase(unique(all(vy)), vy.end());

	auto f = [&](P a, P b) {return max(a, b); };
	int sz[2] = { vx.size(),vy.size()};

	SegT<P> st[2][2];
	ll sum = 0;
	rep(i, 2)rep(j, 2) {
		st[i][j].init(sz[i], P{ -1,-1 }, f);
	}

	auto comp = [&](P a, P b) {
		return a <= b;
	};
	auto del = [&](int id) {
		int cy = lower_bound(all(vy), y[id]) - vy.begin();
		int cx = lower_bound(all(vx), x[id]) - vx.begin();
		sum -= l[id];
		if (x[id] < 0) {
			st[1][0].update(cy, { -1,-1 });
		}
		else if (x[id] == h) {
			st[1][1].update(cy, { -1,-1 });
		}
		else if (y[id] < 0) {
			st[0][0].update(cx, { -1,-1 });
		}
		else {
			st[0][1].update(cx, { -1,-1 });
		}
	};
	map<int, P> mp[2][2];
	rep(i, n) {
		if (x[i] < 0) {
			if (mp[1][0].find(y[i]) != mp[1][0].end()) {
				P p = mp[1][0][y[i]];
				del(p.second);
				l[i] += p.first;
				mp[1][0].erase(y[i]);
			}
		}
		else if (x[i] == h) {
			if (mp[1][1].find(y[i]) != mp[1][1].end()) {
				P p = mp[1][1][y[i]];
				del(p.second);
				l[i] += p.first;
				mp[1][1].erase(y[i]);
			}
		}
		else if (y[i] < 0) {
			if (mp[0][0].find(x[i]) != mp[0][0].end()) {
				P p = mp[0][0][x[i]];
				del(p.second);
				l[i] += p.first;
				mp[0][0].erase(x[i]);
			}
		}
		else {
			if (mp[0][1].find(x[i]) != mp[0][1].end()) {
				P p = mp[0][1][x[i]];
				del(p.second);
				l[i] += p.first;
				mp[0][1].erase(x[i]);
			}
		}
		int cx = lower_bound(all(vx), x[i]) - vx.begin();
		int cy = lower_bound(all(vy), y[i]) - vy.begin();
		if (x[i] < 0) {
			int z = lower_bound(all(vx), l[i]) - vx.begin();
			P pr = { vx.size(),-1 };
			int cr = st[0][0].searchri(0, P{ y[i],-1}, comp);
			if (cr < vx.size()) {
				P p = st[0][0].query(cr, cr + 1);
				chmin(pr, p);
			}
			cr = st[0][1].searchri(0, P{ w-1-y[i],-1}, comp);
			if (cr < vx.size()) {
				P p = st[0][1].query(cr, cr + 1);
				chmin(pr, p);
			}
			if (pr.first < z) {
				int to = pr.second;
				del(to);
			}
			else {
				if (l[i] <= h) {
					st[1][0].update(cy, { l[i] - 1,i });
					sum += l[i];
					mp[1][0][y[i]] = { l[i],i };
				}
			}
		}
		else if (x[i] == h) {
			int z = lower_bound(all(vx), h - l[i]) - vx.begin();
			P pr = { -1,-1 };
			int cl = st[0][0].searchle(vx.size() - 1, P{ y[i],-1}, comp);
			if (cl >= 0) {
				P p = st[0][0].query(cl, cl + 1);
				chmax(pr, p);
			}
			cl = st[0][1].searchle(vx.size() - 1, P{ w-1-y[i],-1}, comp);
			if (cl >= 0) {
				P p = st[0][1].query(cl, cl + 1);
				chmax(pr, p);
			}
			if (pr.first >= z) {
				int to = pr.second;
				del(to);
			}
			else {
				if (l[i] <= h) {
					st[1][1].update(cy, { h - l[i],i });
					sum += l[i];
					mp[1][1][y[i]] = { l[i],i };
				}
			}
		}
		else if (y[i] < 0) {
			int z = lower_bound(all(vy), l[i]) - vy.begin();
			P pr = { vy.size(),-1};
			int c = st[1][0].searchri(0, { x[i],-1}, comp);
			if (c<vy.size()) {
				P p = st[1][0].query(c, c + 1);
				chmin(pr, p);
			}
			c = st[1][1].searchri(0, { h-1-x[i],-1}, comp);
			if (c < vy.size()) {
				P p = st[1][1].query(c, c + 1);
				chmin(pr, p);
			}
			if (pr.first < z) {
				int to = pr.second;
				del(to);
			}
			else {
				if (l[i] <= w) {
					st[0][0].update(cx, { l[i] - 1 ,i });
					sum += l[i];
					mp[0][0][x[i]] = { l[i],i };
				}
			}
		}
		else {
			int z = lower_bound(all(vy), w - l[i]) - vy.begin();
			P pr = { -1,-1 };
			int c = st[1][0].searchle(vy.size() - 1, { x[i],-1}, comp);
			if (c >= 0) {
				P p = st[1][0].query(c, c + 1);
				chmax(pr, p);
			}
			c = st[1][1].searchle(vy.size() - 1, { h-1-x[i],-1}, comp);
			if (c >= 0) {
				P p = st[1][1].query(c, c + 1);
				chmax(pr,p);
			}
			if (pr.first >= z) {
				int to = pr.second;
				del(to);
			}
			else {
				if (l[i] <= w) {
					st[0][1].update(cx, { w - l[i],i });
					sum += l[i];
					mp[0][1][x[i]] = { l[i],i };
				}
			}
		}
	}
	cout << sum << "\n";
}



signed main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	//cout << fixed << setprecision(12);
	//init_f();
	//init();
	//while(true)
	//expr();
	//int t; cin >> t; rep(i, t)
	solve();
	return 0;
}