/*

This Submission is to determine how many 120/240 min const. delivery point there are.

//info
120 req. steps <= 5
*/
#define  _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <algorithm>
#include <utility>
#include <functional>
#include <cstring>
#include <queue>
#include <stack>
#include <math.h>
#include <iterator>
#include <vector>
#include <string>
#include <set>
#include <math.h>
#include <iostream>
#include <random>
#include<map>
#include <iomanip>
#include <time.h>
#include <stdlib.h>
#include <list>
#include <typeinfo>
#include <list>
#include <set>
#include <cassert>
#include<fstream>
#include <unordered_map>
#include <cstdlib>
#include <complex>
#include <cctype>
#include <bitset>
using namespace std;
typedef string::const_iterator State;
#define Ma_PI 3.141592653589793
#define eps 1e-5
#define LONG_INF 1e18
#define GOLD 1.61803398874989484820458
#define MAX_MOD 1000000007LL
#define MOD 998244353LL
#define seg_size 262144
#define REP(a,b) for(long long a = 0;a < b;++a)

unsigned long xor128() {
	static unsigned long x = time(NULL), y = 362436069, z = 521288629, w = 88675123;
	unsigned long t = (x ^ (x << 11));
	x = y; y = z; z = w;
	return (w = (w ^ (w >> 19)) ^ (t ^ (t >> 8)));
}
double dot(complex<double> a, complex<double> b) {
	return a.real() * b.real() + a.imag() * b.imag();
}
double gyaku_dot(complex<double> a, complex<double> b) {
	return a.real() * b.imag() - a.imag() * b.real();
}
double leng(complex<double> a) {
	return sqrt(a.real() * a.real() + a.imag() * a.imag());
}
double angles(complex<double> a, complex<double> b) {
	double cosine = dot(a, b) / (leng(a) * leng(b));
	double sine = gyaku_dot(a, b) / (leng(a) * leng(b));
	double kaku = acos(min((double)1.0, max((double)-1.0, cosine)));
	if (sine <= 0) {
		kaku = 2 * Ma_PI - kaku;
	}
	return kaku;
}
vector<int> convex_hull(vector<complex<double>> a) {
	vector<int> ans;
	double now_minnest = a[0].real();
	int now_itr = 0;
	REP(i, a.size()) {
		if (now_minnest > a[i].real()) {
			now_minnest = a[i].real();
			now_itr = i;
		}
	}
	ans.push_back(now_itr);
	complex<double> ba(0, 1);
	while (true) {
		int now_go = 0;
		double now_min = 0;
		double now_length = 0;
		int starter = ans[ans.size() - 1];
		for (int i = 0; i < a.size(); ++i) {
			if (i != starter) {
				double goa = angles(ba, a[i] - a[starter]);
				if (goa - now_min >= eps || (abs(goa - now_min) <= eps && (abs(a[i] - a[starter]) - now_length) >= eps)) {
					now_min = goa;
					now_go = i;
					now_length = abs(a[i] - a[starter]);
				}
			}
		}
		if (now_go == ans[0]) break;
		ans.push_back(now_go);
		ba = complex<double>(a[now_go] - a[starter]);
	}
	return ans;
}
tuple<long long, long long, long long> info[200000];
vector<long long> lane[200000];
vector<long long> column[200000];
long long x[200000];
long long y[200000];
long long x_visited[200000];
long long y_visited[200000];
long long x_det[200000];
long long y_det[200000];
int main() {
#define int long long
	int r, c;
	cin >> r >> c;
	int n;
	cin >> n;
	REP(i, n) {
		long long a, b, c;
		cin >> a >> b >> c;
		a--;
		b--;
		info[i] = make_tuple(a, b, c);
		lane[a].push_back(i);
		column[b].push_back(i);
	}
	queue<int> next_go;
	for (int i = 0; i < r; ++i) {
		if (lane[i].size() == 0) continue;
		if (x_visited[i] == 1) continue;
		next_go.push(lane[i][0]);
		if (y_det[get<1>(info[lane[i][0]])] == 0) {
			y[get<1>(info[lane[i][0]])] = get<2>(info[lane[i][0]]);
			y_det[get<1>(info[lane[i][0]])] = 1;
		}
		if (x_det[i] == 0) {
			x_det[i] = 1;
			x[i] = get<2>(info[lane[i][0]]) - y[get<1>(info[lane[i][0]])];
		}
		long long now_x = LONG_INF;
		long long now_y = LONG_INF;
		while (next_go.empty() == false) {
			int now = next_go.front(); next_go.pop();
			now_x = min(now_x, x[get<0>(info[now])]);
			now_y = min(now_y, y[get<1>(info[now])]);
			if (x_visited[get<0>(info[now])] == 0) {
				x_visited[get<0>(info[now])] = 1;
				int target = get<0>(info[now]);
				for (int q = 0; q < lane[target].size(); ++q) {
					int go = lane[target][q];
					if (go == now) continue;
					if (y_det[get<1>(info[go])] == 0) {
						//make determination
						y_det[get<1>(info[go])] = 1;
						y[get<1>(info[go])] = get<2>(info[go]) - x[get<0>(info[go])];
					}
					else {
						if (y[get<1>(info[go])] != get<2>(info[go]) - x[get<0>(info[go])]) {
							cout << "No" << endl;
							return 0;
						}
					}
					if (y_visited[get<1>(info[go])] == 0) {
						next_go.push(go);
					}
				}
			}
			if (y_visited[get<1>(info[now])] == 0) {
				y_visited[get<1>(info[now])] = 1;
				int target = get<1>(info[now]);
				for (int q = 0; q < column[target].size(); ++q) {
					int go = column[target][q];
					if (go == now) continue;
					if (x_det[get<0>(info[go])] == 0) {
						//make determination
						x_det[get<0>(info[go])] = 1;
						x[get<0>(info[go])] = get<2>(info[go]) - y[get<1>(info[go])];
					}
					else {
						if (x[get<0>(info[go])] != get<2>(info[go]) - y[get<1>(info[go])]) {
							cout << "No" << endl;
							return 0;
						}
					}
					if (x_visited[get<0>(info[go])] == 0) {
						next_go.push(go);
					}
				}
			}
		}
		if (now_x + now_y < 0) {
			cout << "No" << endl;
			return 0;
		}
	}
	REP(i, n) {
		if (x[get<0>(info[i])] + y[get<1>(info[i])] != get<2>(info[i])) {
			cout << "No" << endl;
			return 0;
		}
	}
	cout << "Yes" << endl;
}

Measured memory_bytes: 28288