#include <bits/stdc++.h>
using namespace std;
using lint = long long;
const lint mod = 1e9 + 7;
#define all(x) (x).begin(), (x).end()
#define bitcount(n) __builtin_popcountl((lint)(n))
#define fcout cout << fixed << setprecision(15)
#define highest(x) (63 - __builtin_clzl(x))
template<class T> inline void YES(T condition){ if(condition) cout << "YES" << endl; else cout << "NO" << endl; }
template<class T> inline void Yes(T condition){ if(condition) cout << "Yes" << endl; else cout << "No" << endl; }
template<class T = string, class U = char>int character_count(T text, U character){ int ans = 0; for(U i: text){ ans += (i == character); } return ans; }
lint power(lint base, lint exponent, lint module){ if(exponent % 2){ return power(base, exponent - 1, module) * base % module; }else if(exponent){ lint root_ans = power(base, exponent / 2, module); return root_ans * root_ans % module; }else{ return 1; }}
struct position{ int y, x; }; position mv[4] = {{0, -1}, {1, 0}, {0, 1}, {-1, 0}}; // double euclidean(position first, position second){ return sqrt((second.x - first.x) * (second.x - first.x) + (second.y - first.y) * (second.y - first.y)); }
template<class T, class U> string to_string(pair<T, U> x){ return to_string(x.first) + "," + to_string(x.second); } string to_string(string x){ return x; }
template<class itr> void array_output(itr start, itr goal){ string ans; for(auto i = start; i != goal; i++) ans += to_string(*i) + " "; if(!ans.empty()) ans.pop_back(); cout << ans << endl; }
template<class itr> void cins(itr first, itr last){ for(auto i = first; i != last; i++){ cin >> (*i); } }
template<class T> T gcd(T a, T b){ if(a && b){ return gcd(min(a, b), max(a, b) % min(a, b)); }else{ return a; }} template<class T> T lcm(T a, T b){ return a / gcd(a, b) * b; }
struct combination{ vector<lint> fact, inv; combination(int sz) : fact(sz + 1), inv(sz + 1){ fact[0] = 1; for(int i = 1; i <= sz; i++){ fact[i] = fact[i - 1] * i % mod; } inv[sz] = power(fact[sz], mod - 2, mod); for(int i = sz - 1; i >= 0; i--){ inv[i] = inv[i + 1] * (i + 1) % mod; } } lint C(int p, int q) const{ if(q < 0 || p < q) return 0; return (fact[p] * inv[q] % mod * inv[p - q] % mod); } };
template<class itr> bool next_sequence(itr first, itr last, int max_bound){ itr now = last; while(now != first){ now--; (*now)++; if((*now) == max_bound){ (*now) = 0; }else{ return true; } } return false; }

template< typename Monoid >
struct SegmentTree
{
    using F = function< Monoid(Monoid, Monoid) >;
    
    int sz;
    vector< Monoid > seg;
    
    const F f;
    const Monoid M1;
    
    SegmentTree(int n, const F f, const Monoid &M1) : f(f), M1(M1)
    {
        sz = 1;
        while(sz < n) sz <<= 1;
        seg.assign(2 * sz, M1);
    }
    
    void set(int k, const Monoid &x)
    {
        seg[k + sz] = x;
    }
    
    void build()
    {
        for(int k = sz - 1; k > 0; k--) {
            seg[k] = f(seg[2 * k + 0], seg[2 * k + 1]);
        }
    }
    
    void update(int k, const Monoid &x)
    {
        k += sz;
        seg[k] = x;
        while(k >>= 1) {
            seg[k] = f(seg[2 * k + 0], seg[2 * k + 1]);
        }
    }
    
    Monoid query(int a, int b)
    {
        Monoid L = M1, R = M1;
        for(a += sz, b += sz; a < b; a >>= 1, b >>= 1) {
            if(a & 1) L = f(L, seg[a++]);
            if(b & 1) R = f(seg[--b], R);
        }
        return f(L, R);
    }
    
    Monoid operator[](const int &k) const
    {
        return seg[k + sz];
    }
};

int main(){
    lint H, W;
    int N;
    cin >> H >> W >> N;
    lint X[N], Y[N], L[N];
    vector<lint> Xs, Ys;
    for(int i = 0; i < N; i++){
        cin >> X[i] >> Y[i] >> L[i];
        if(1 <= X[i] && X[i] <= W){
            Xs.push_back(X[i]);
        }
        if(1 <= Y[i] && Y[i] <= H){
            Ys.push_back(Y[i]);
        }
    }
    sort(all(Xs));
    Xs.erase(unique(all(Xs)), Xs.end());
    sort(all(Ys));
    Ys.erase(unique(all(Ys)), Ys.end());
    int h = int(Ys.size()), w = int(Xs.size());
    SegmentTree<lint> up(w, [](int a, int b){ return max(a, b); }, 0);
    SegmentTree<lint> down(w, [](int a, int b){ return max(a, b); }, 0);
    SegmentTree<lint> left(h, [](int a, int b){ return max(a, b); }, 0);
    SegmentTree<lint> right(h, [](int a, int b){ return max(a, b); }, 0);
    for(int i = 0; i < N; i++){
        if(X[i] == 0){
            int pos = int(lower_bound(all(Ys), Y[i]) - Ys.begin());
            lint len = left[pos] + L[i];
            int up_collision, down_collision;
            lint up_pos, down_pos, right_pos;
            {
                int low = -1, high = w; // (low, high]
                while(low + 1 < high){
                    int mid = (low + high) / 2;
                    if(up.query(0, mid + 1) >= Y[i]){
                        high = mid;
                    }else{
                        low = mid;
                    }
                }
                up_collision = high;
                if(high == w){
                    up_pos = 1e18;
                }else{
                    up_pos = Xs[high];
                }
            }
            {
                int low = -1, high = w; // (low, high]
                while(low + 1 < high){
                    int mid = (low + high) / 2;
                    if(down.query(0, mid + 1) >= H - Y[i]){
                        high = mid;
                    }else{
                        low = mid;
                    }
                }
                down_collision = high;
                if(high == w){
                    down_pos = 1e18;
                }else{
                    down_pos = Xs[high];
                }
            }
            {
                right_pos = W - right[pos] + 1;
            }
            if(len < min({up_pos, down_pos, right_pos})){
                left.update(pos, len);
            }else if(up_pos < down_pos && up_pos < right_pos){
                left.update(pos, 0);
                up.update(up_collision, 0);
            }else if(down_pos < up_pos && down_pos < right_pos){
                left.update(pos, 0);
                down.update(down_collision, 0);
            }else{
                left.update(pos, 0);
                right.update(pos, 0);
            }
        }
        
        if(X[i] == W + 1){
            int pos = int(lower_bound(all(Ys), Y[i]) - Ys.begin());
            lint len = right[pos] + L[i];
            int up_collision, down_collision;
            lint up_pos, down_pos, left_pos;
            {
                int low = -1, high = w; // (low, high]
                while(low + 1 < high){
                    int mid = (low + high) / 2;
                    if(up.query(w - mid - 1, w) >= Y[i]){
                        high = mid;
                    }else{
                        low = mid;
                    }
                }
                up_collision = high;
                if(high == w){
                    up_pos = 1e18;
                }else{
                    up_pos = Xs[w - high - 1];
                }
            }
            {
                int low = -1, high = w; // (low, high]
                while(low + 1 < high){
                    int mid = (low + high) / 2;
                    if(down.query(w - mid - 1, w) >= H - Y[i]){
                        high = mid;
                    }else{
                        low = mid;
                    }
                }
                down_collision = high;
                if(high == w){
                    down_pos = 1e18;
                }else{
                    down_pos = Xs[w - high - 1];
                }
            }
            {
                left_pos = W - left[pos] + 1;
            }
            if(len < min({up_pos, down_pos, left_pos})){
                right.update(pos, len);
            }else if(up_pos < down_pos && up_pos < left_pos){
                right.update(pos, 0);
                up.update(up_collision, 0);
            }else if(down_pos < up_pos && down_pos < left_pos){
                right.update(pos, 0);
                down.update(down_collision, 0);
            }else{
                right.update(pos, 0);
                left.update(pos, 0);
            }
        }
        
        if(Y[i] == 0){
            int pos = int(lower_bound(all(Xs), X[i]) - Xs.begin());
            lint len = up[pos] + L[i];
            int left_collision, right_collision;
            lint left_pos, right_pos, down_pos;
            {
                int low = -1, high = h; // (low, high]
                while(low + 1 < high){
                    int mid = (low + high) / 2;
                    if(left.query(0, mid + 1) >= X[i]){
                        high = mid;
                    }else{
                        low = mid;
                    }
                }
                left_collision = high;
                if(high == h){
                    left_pos = 1e18;
                }else{
                    left_pos = Ys[high];
                }
            }
            {
                int low = -1, high = h; // (low, high]
                while(low + 1 < high){
                    int mid = (low + high) / 2;
                    if(right.query(0, mid + 1) >= W - X[i]){
                        high = mid;
                    }else{
                        low = mid;
                    }
                }
                right_collision = high;
                if(high == h){
                    right_pos = 1e18;
                }else{
                    right_pos = Ys[high];
                }
            }
            {
                down_pos = H - down[pos] + 1;
            }
            if(len < min({left_pos, right_pos, down_pos})){
                up.update(pos, len);
            }else if(left_pos < right_pos && left_pos < down_pos){
                up.update(pos, 0);
                left.update(left_collision, 0);
            }else if(right_pos < left_pos && right_pos < down_pos){
                up.update(pos, 0);
                right.update(right_collision, 0);
            }else{
                up.update(pos, 0);
                down.update(pos, 0);
            }
        }
        
        if(Y[i] == H + 1){
            int pos = int(lower_bound(all(Xs), X[i]) - Xs.begin());
            lint len = down[pos] + L[i];
            int left_collision, right_collision;
            lint left_pos, right_pos, up_pos;
            {
                int low = -1, high = h; // (low, high]
                while(low + 1 < high){
                    int mid = (low + high) / 2;
                    if(left.query(h - mid - 1, h) >= X[i]){
                        high = mid;
                    }else{
                        low = mid;
                    }
                }
                left_collision = high;
                if(high == h){
                    left_pos = 1e18;
                }else{
                    left_pos = Ys[h - high - 1];
                }
            }
            {
                int low = -1, high = h; // (low, high]
                while(low + 1 < high){
                    int mid = (low + high) / 2;
                    if(right.query(h - mid - 1, h) >= W - X[i]){
                        high = mid;
                    }else{
                        low = mid;
                    }
                }
                right_collision = high;
                if(high == w){
                    right_pos = 1e18;
                }else{
                    right_pos = Ys[h - high - 1];
                }
            }
            {
                up_pos = H - up[pos] + 1;
            }
            if(len < min({left_pos, right_pos, up_pos})){
                down.update(pos, len);
            }else if(left_pos < right_pos && left_pos < up_pos){
                down.update(pos, 0);
                left.update(left_collision, 0);
            }else if(right_pos < left_pos && right_pos < up_pos){
                down.update(pos, 0);
                right.update(right_collision, 0);
            }else{
                down.update(pos, 0);
                up.update(pos, 0);
            }
        }
    }
    lint ans = 0;
    for(int i = 0; i < w; i++){
        ans += up[i] + down[i];
    }
    for(int i = 0; i < h; i++){
        ans += left[i] + right[i];
    }
    cout << ans << endl;
}