#include <iostream>
#include <map>
#include <vector>

using namespace std;

void failure () {
  cout << "No" << endl;
  exit(0);
}

typedef long long ll;

const ll INF = 1e12 + 5;
const int MAX_N = 2e5 + 5;
const int COLS = 1e5;

int row (int idx) {
  return idx;
}

int col (int idx) {
  return idx + COLS;
}

int vis [MAX_N];
ll val [MAX_N];
vector<pair<int, ll>> adj [MAX_N];

void dfs (int u, ll &rm, ll &cm) {
  vis[u] = 1;
  if (u < COLS) rm = min(rm, val[u]);
  else cm = min(cm, val[u]);
  
  for (auto nxt : adj[u]) {
    if (!vis[nxt.first]) {
      val[nxt.first] = nxt.second - val[u];
      dfs(nxt.first, rm, cm);
    } else if (val[nxt.first] != nxt.second - val[u]) {
      failure();
    }
  }
}

int main () {
  ios::sync_with_stdio(false);
  
  int R, C;
  cin >> R >> C;

  int n;
  cin >> n;

  for (int i = 0; i < n; i++) {
    int r, c, a;
    cin >> r >> c >> a;

    adj[row(r)].push_back({col(c), a});
    adj[col(c)].push_back({row(r), a});
  }

  for (int i = 1; i <= R; i++) {
    if (!vis[row(i)]) {
      ll rm = INF, cm = INF;
      dfs(row(i), rm, cm);
      if (rm + cm < 0) failure();
    }
  }

  cout << "Yes" << endl;
}
