#include <bits/stdc++.h>
#define rep(i, a, n) for(int i = a; i < (n); i++)
using namespace std;
using ll = long long;
using P = pair<int, int>;
const int INF = 1001001001;
const ll LINF = 1001002003004005006ll;
//const int mod = 1000000007;
//const int mod = 998244353;

int main()
{
  int h, w, k;
  cin >> h >> w >> k;
  ll ans = 0;
  map<P, ll> mp;
  rep(i, 0, k) {
    int a, b; ll c;
    cin >> a >> b >> c;
    a--; b--;
    mp[P(a, b)] = c;
  }
  rep(i, 0, h) {
    rep(j, 0, w) {
      rep(ni, 0, h) {
        rep(nj, 0, w) {
          if (ni + nj >= i + j && ni - nj >= i - j) ans += mp[P(ni, nj)];
        }
      }
    }
  }
  cout << ans << endl;
  return 0;
}