#include <iostream>
#include <vector>
#include <cstdio>
#include <sstream>
#include <map>
#include <string>
#include <algorithm>
#include <queue>
#include <cmath>
#include <functional>
#include <set>
#include <ctime>
#include <random>
#include <chrono>
#include <cassert>
using namespace std;

namespace {
  using Integer = long long; //__int128;
  template<class T> istream& operator >> (istream& is, vector<T>& vec){for(T& val: vec) is >> val; return is;}
  template<class T> istream& operator ,  (istream& is, T& val){ return is >> val;}
  template<class T> ostream& operator << (ostream& os, const vector<T>& vec){for(int i=0; i<vec.size(); i++) os << vec[i] << (i==vec.size()-1?"":" "); return os;}
  template<class T> ostream& operator ,  (ostream& os, const T& val){ return os << " " << val;}

  template<class H> void print(const H& head){ cout << head; }
  template<class H, class ... T> void print(const H& head, const T& ... tail){ cout << head << " "; print(tail...); }
  template<class ... T> void println(const T& ... values){ print(values...); cout << endl; }

  template<class H> void eprint(const H& head){ cerr << head; }
  template<class H, class ... T> void eprint(const H& head, const T& ... tail){ cerr << head << " "; eprint(tail...); }
  template<class ... T> void eprintln(const T& ... values){ eprint(values...); cerr << endl; }

  class range{
    long long start_, end_, step_;
   public:
    struct range_iterator{
      long long val, step_;
      range_iterator(long long v, long long step) : val(v), step_(step) {}
      long long operator * (){return val;}
      void operator ++ (){val += step_;}
      bool operator != (range_iterator& x){return step_ > 0 ? val < x.val : val > x.val;}
    };
    range(long long len) : start_(0), end_(len), step_(1) {}
    range(long long start, long long end) : start_(start), end_(end), step_(1) {}
    range(long long start, long long end, long long step) : start_(start), end_(end), step_(step) {}
    range_iterator begin(){ return range_iterator(start_, step_); }
    range_iterator   end(){ return range_iterator(  end_, step_); }
  };

  string operator "" _s (const char* str, size_t size){ return move(string(str)); }
  constexpr Integer my_pow(Integer x, Integer k, Integer z=1){return k==0 ? z : k==1 ? z*x : (k&1) ? my_pow(x*x,k>>1,z*x) : my_pow(x*x,k>>1,z);}
  constexpr Integer my_pow_mod(Integer x, Integer k, Integer M, Integer z=1){return k==0 ? z%M : k==1 ? z*x%M : (k&1) ? my_pow_mod(x*x%M,k>>1,M,z*x%M) : my_pow_mod(x*x%M,k>>1,M,z);}
  constexpr unsigned long long operator "" _ten (unsigned long long value){ return my_pow(10,value); }

  inline int k_bit(Integer x, int k){return (x>>k)&1;} //0-indexed

  mt19937 mt(chrono::duration_cast<chrono::nanoseconds>(chrono::steady_clock::now().time_since_epoch()).count());

  template<class T> string join(const vector<T>& v, const string& sep){
    stringstream ss; for(int i=0; i<v.size(); i++){ if(i>0) ss << sep; ss << v[i]; } return ss.str();
  }

  string operator * (string s, int k){ string ret; while(k){ if(k&1) ret += s; s += s; k >>= 1; } return ret; }

}

constexpr long long mod = 9_ten + 7;

int dx[] = {0, 1, 1,};
int dy[] = {1, 0, 1,};

int main(){
  int h,w;
  cin >> h,w;
  int n;
  cin >> n;
  h++; w++;

  vector<int> r(n),c(n),a(n);
  for(auto i : range(n) ){
    scanf("%d%d%d", &r[i],&c[i],&a[i]);
  }

  map<int, vector<pair<int,int>>> v;
  for(auto i : range(n) ){
    v[r[i]  ].push_back({c[i]+h,a[i]});
    v[c[i]+h].push_back({r[i]  ,a[i]});
  }

  map<int, long long> wv;

  for(auto& p : v ){
    if(wv.count(p.first)) continue;
    set<long long> wr;
    set<long long> wc;
    function<bool(int)> dfs = [&](int pos){
      if(pos < h) wr.insert(wv[pos]);
      else wc.insert(wv[pos]);

      for(auto& next: v[pos] ){
        int nx = next.first;
        long long aa = next.second;
        if(wv.count(nx)){
          if(wv[nx]+wv[pos] != aa) return false;
          else continue;
        }
        wv[nx] = aa - wv[pos];
        if( dfs(nx) == false ) return false;
      }
      return true;
    };

    wv[p.first] = 0;
    if( !dfs(p.first) ){
      println("No");
      return 0;
    }

    if( *wr.begin() + *wc.begin() < 0 ){
      println("No");
      return 0;
    }
  }

  println("Yes");


  return 0;
}


Measured memory_bytes: 35840