#include <cstdio>
#include <algorithm>
#include <stack>
#include <queue>
#include <deque>
#include <vector>
#include <string>
#include <string.h>
#include <cstdlib>
#include <ctime>
#include <cmath>
#include <map>
#include <set>
#include <iostream>
#include <sstream>
#include <numeric>
#include <cctype>
#include <bitset>
#include <cassert>
#define fi first
#define se second
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define rrep(i,n) for(int i = 1; i <= (n); ++i)
#define drep(i,n) for(int i = (n)-1; i >= 0; --i)
#define each(it,c) for(__typeof((c).begin()) it=(c).begin();it!=(c).end();it++)
#define rng(a) a.begin(),a.end()
#define maxs(x,y) x = max(x,y)
#define mins(x,y) x = min(x,y)
#define pb push_back
#define sz(x) (int)(x).size()
#define pcnt __builtin_popcount
#define uni(x) x.erase(unique(rng(x)),x.end())
#define snuke srand((unsigned)clock()+(unsigned)time(NULL));
#define df(x) int x = in()
#define dame { puts("0"); return 0;}
#define show(x) cout<<#x<<" = "<<x<<endl;
#define PQ(T) priority_queue<T,vector<T>,greater<T> >
using namespace std;
typedef long long int ll;
typedef pair<int,int> P;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<ll> vl;
typedef vector<P> vp;
inline int in() { int x; scanf("%d",&x); return x;}
inline void priv(vi a) { rep(i,sz(a)) printf("%d%c",a[i],i==sz(a)-1?'\n':' ');}
template<typename T>istream& operator>>(istream&i,vector<T>&v)
{rep(j,sz(v))i>>v[j];return i;}
template<typename T>string join(vector<T>&v)
{stringstream s;rep(i,sz(v))s<<' '<<v[i];return s.str().substr(1);}
template<typename T>ostream& operator<<(ostream&o,vector<T>&v)
{if(sz(v))o<<join(v);return o;}
template<typename T1,typename T2>istream& operator>>(istream&i,pair<T1,T2>&v)
{return i>>v.fi>>v.se;}
template<typename T1,typename T2>ostream& operator<<(ostream&o,pair<T1,T2>&v)
{return o<<v.fi<<","<<v.se;}
const int MX = 100005, INF = 1001001001;
const ll LINF = 1e18;
const double eps = 1e-10;

vi tx[MX], cx[MX];
vi ty[MX], cy[MX];

int main() {
  int h, w;
  scanf("%d%d",&h,&w);
  int n;
  scanf("%d",&n);
  rep(i,n) {
    int x, y, a;
    scanf("%d%d%d",&x,&y,&a);
    --x; --y;
    tx[x].pb(y); cx[x].pb(a);
    ty[y].pb(x); cy[y].pb(a);
  }
  vl sx(MX,LINF), sy(MX,LINF);
  rep(i,MX) {
    if (sx[i] != LINF) continue;
    queue<int> qx, qy;
    qx.push(i);
    sx[i] = 0;
    ll lx = 0, ly = LINF;
    while (sz(qx)) {
      while (sz(qx)) {
        int x = qx.front(); qx.pop();
        rep(j,sz(tx[x])) {
          int y = tx[x][j], c = cx[x][j];
          ll ns = c-sx[x];
          if (sy[y] == LINF) {
            sy[y] = ns;
            mins(ly,ns);
            qy.push(y);
          } else {
            if (sy[y] != ns) {
              puts("No");
              return 0;
            }
          }
        }
      }
      while (sz(qy)) {
        int y = qy.front(); qy.pop();
        rep(j,sz(ty[y])) {
          int x = ty[y][j], c = cy[y][j];
          ll ns = c-sy[y];
          if (sx[x] == LINF) {
            sx[x] = ns;
            mins(lx,ns);
            qx.push(x);
          } else {
            if (sx[x] != ns) {
              puts("No");
              return 0;
            }
          }
        }
      }
    }
    if (lx+ly < 0) {
      puts("No");
      return 0;
    }
  }
  puts("Yes");
  return 0;
}







Measured memory_bytes: 23680