using System;
using System.Collections.Generic;
using System.Linq;
using System.IO;
class Program
{
const int M = 1000000007;
const double eps = 1e-9;
static int[] dd = { 0, 1, 0, -1, 0 };
static void Main()
{
var sw = new StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false };
var sc = new Scan();
int r, c;
sc.Multi(out r, out c);
int n = sc.Int;
var nodes = new SortedDictionary<int, int>[r];
for (int i = 0; i < r; i++)
{
nodes[i] = new SortedDictionary<int, int>();
}
var min = new int[c];
for (int i = 0; i < c; i++)
{
min[i] = M;
}
for (int i = 0; i < n; i++)
{
var a = sc.IntArr;
--a[0];
--a[1];
nodes[a[0]].Add(a[1], a[2]);
min[a[1]] = Math.Min(min[a[1]], a[2]);
}
var ed_to = new List<int>[c];
var ed_cost = new List<int>[c];
for (int i = 0; i < c; i++)
{
ed_to[i] = new List<int>();
ed_cost[i] = new List<int>();
}
for (int i = 0; i < r; i++)
{
int prc = -1, prcost = -1;
foreach (var item in nodes[i])
{
if (prc > -1)
{
ed_to[prc].Add(item.Key);
ed_to[item.Key].Add(prc);
ed_cost[prc].Add(item.Value - prcost);
ed_cost[item.Key].Add(prcost - item.Value);
}
prc = item.Key;
prcost = item.Value;
}
}
var dis = new int[c];
for (int i = 0; i < c; i++)
{
dis[i] = -M * 2;
}
for (int i = 0; i < c; i++)
{
if (dis[i] == -M * 2)
{
var q = new Queue<int>();
q.Enqueue(i);
dis[i] = 0;
while (q.Any())
{
var p = q.Dequeue();
for (int j = 0; j < ed_to[p].Count; j++)
{
var nex = ed_to[p][j];
if (dis[nex] == -M * 2)
{
dis[nex] = dis[p] + ed_cost[p][j];
q.Enqueue(nex);
}
else if (dis[nex] != dis[p] + ed_cost[p][j])
{
DBG("No");
return;
}
if (min[i] + dis[nex] < 0 || min[p] + ed_cost[p][j] < 0)
{
DBG("No");
return;
}
min[nex] = Math.Min(min[p] + ed_cost[p][j], min[nex]);
}
}
}
}
sw.WriteLine("Yes");
sw.Flush();
}
static void swap<T>(ref T a, ref T b) { var t = a; a = b; b = t; }
static void swap<T>(IList<T> a, int i, int j) { var t = a[i]; a[i] = a[j]; a[j] = t; }
static T Max<T>(params T[] a) { return a.Max(); }
static T Min<T>(params T[] a) { return a.Min(); }
static void DBG<T>(params T[] a) { Console.WriteLine(string.Join(" ", a)); }
static void DBG(params object[] a) { Console.WriteLine(string.Join(" ", a)); }
static T[] copy<T>(IList<T> a)
{
var ret = new T[a.Count];
for (int i = 0; i < a.Count; i++) ret[i] = a[i];
return ret;
}
}
class Scan
{
public int Int { get { return int.Parse(Str); } }
public long Long { get { return long.Parse(Str); } }
public double Double { get { return double.Parse(Str); } }
public string Str { get { return Console.ReadLine().Trim(); } }
public int[] IntArr { get { return StrArr.Select(int.Parse).ToArray(); } }
public int[] IntArrWithSep(char sep) { return Str.Split(sep).Select(int.Parse).ToArray(); }
public long[] LongArr { get { return StrArr.Select(long.Parse).ToArray(); } }
public double[] DoubleArr { get { return StrArr.Select(double.Parse).ToArray(); } }
public string[] StrArr { get { return Str.Split(); } }
T cv<T>(string inp)
{
if (typeof(T).Equals(typeof(int))) return (T)Convert.ChangeType(int.Parse(inp), typeof(T));
if (typeof(T).Equals(typeof(long))) return (T)Convert.ChangeType(long.Parse(inp), typeof(T));
if (typeof(T).Equals(typeof(double))) return (T)Convert.ChangeType(double.Parse(inp), typeof(T));
if (typeof(T).Equals(typeof(char))) return (T)Convert.ChangeType(inp[0], typeof(T));
return (T)Convert.ChangeType(inp, typeof(T));
}
public void Multi<T>(out T a) { a = cv<T>(Str); }
public void Multi<T, U>(out T a, out U b)
{ var ar = StrArr; a = cv<T>(ar[0]); b = cv<U>(ar[1]); }
public void Multi<T, U, V>(out T a, out U b, out V c)
{ var ar = StrArr; a = cv<T>(ar[0]); b = cv<U>(ar[1]); c = cv<V>(ar[2]); }
public void Multi<T, U, V, W>(out T a, out U b, out V c, out W d)
{ var ar = StrArr; a = cv<T>(ar[0]); b = cv<U>(ar[1]); c = cv<V>(ar[2]); d = cv<W>(ar[3]); }
public void Multi<T, U, V, W, X>(out T a, out U b, out V c, out W d, out X e)
{ var ar = StrArr; a = cv<T>(ar[0]); b = cv<U>(ar[1]); c = cv<V>(ar[2]); d = cv<W>(ar[3]); e = cv<X>(ar[4]); }
}
class mymath
{
static int Mod = 1000000007;
public void setMod(int m) { Mod = m; }
public bool isprime(long a)
{
if (a < 2) return false;
for (long i = 2; i * i <= a; i++) if (a % i == 0) return false;
return true;
}
public bool[] sieve(int n)
{
var isp = new bool[n + 1];
for (int i = 2; i <= n; i++) isp[i] = true;
for (int i = 2; i * i <= n; i++) if (isp[i]) for (int j = i * i; j <= n; j += i) isp[j] = false;
return isp;
}
public List<int> getprimes(int n)
{
var prs = new List<int>();
var isp = sieve(n);
for (int i = 2; i <= n; i++) if (isp[i]) prs.Add(i);
return prs;
}
public long[][] E(int n)
{
var ret = new long[n][];
for (int i = 0; i < n; i++)
{
ret[i] = new long[n];
ret[i][i] = 1;
}
return ret;
}
public long[][] powmat(long[][] A, long n)
{
if (n == 0) return E(A.Length);
var t = powmat(A, n / 2);
if ((n & 1) == 0) return mulmat(t, t);
return mulmat(mulmat(t, t), A);
}
public long[] mulmat(long[][] A, long[] x)
{
int n = A.Length, m = x.Length;
var ans = new long[n];
for (int i = 0; i < n; i++) for (int j = 0; j < m; j++) ans[i] = (ans[i] + x[j] * A[i][j]) % Mod;
return ans;
}
public long[][] mulmat(long[][] A, long[][] B)
{
int n = A.Length, m = B[0].Length, l = B.Length;
var ans = new long[n][];
for (int i = 0; i < n; i++)
{
ans[i] = new long[m];
for (int j = 0; j < m; j++) for (int k = 0; k < l; k++) ans[i][j] = (ans[i][j] + A[i][k] * B[k][j]) % Mod;
}
return ans;
}
public long[] addmat(long[] x, long[] y)
{
int n = x.Length;
var ans = new long[n];
for (int i = 0; i < n; i++) ans[i] = (x[i] + y[i]) % Mod;
return ans;
}
public long[][] addmat(long[][] A, long[][] B)
{
int n = A.Length, m = A[0].Length;
var ans = new long[n][];
for (int i = 0; i < n; i++) ans[i] = addmat(A[i], B[i]);
return ans;
}
public long powmod(long a, long b)
{
if (a >= Mod) return powmod(a % Mod, b);
if (a == 0) return 0;
if (b == 0) return 1;
var t = powmod(a, b / 2);
if ((b & 1) == 0) return t * t % Mod;
return t * t % Mod * a % Mod;
}
public long inv(long a) { return powmod(a, Mod - 2); }
public long gcd(long a, long b)
{
while (b > 0) { var t = a % b; a = b; b = t; }
return a;
}
public long lcm(long a, long b) { return a * (b / gcd(a, b)); }
public long Comb(int n, int r)
{
if (n < 0 || r < 0 || r > n) return 0;
if (n - r < r) r = n - r;
if (r == 0) return 1;
if (r == 1) return n;
var numerator = new int[r];
var denominator = new int[r];
for (int k = 0; k < r; k++)
{
numerator[k] = n - r + k + 1;
denominator[k] = k + 1;
}
for (int p = 2; p <= r; p++)
{
int pivot = denominator[p - 1];
if (pivot > 1)
{
int offset = (n - r) % p;
for (int k = p - 1; k < r; k += p)
{
numerator[k - offset] /= pivot;
denominator[k] /= pivot;
}
}
}
long result = 1;
for (int k = 0; k < r; k++) if (numerator[k] > 1) result = result * numerator[k] % Mod;
return result;
}
}