#include <bits/stdc++.h>
//#include "bits/stdc++.h"
using namespace std;
typedef long long ll;
//#include "boost/multiprecision/cpp_int.hpp"
//typedef boost::multiprecision::cpp_int ll;
typedef long double dd;
#define i_7 (ll)(1E9+7)
//#define i_7 998244353
#define i_5 i_7-2

ll mod(ll a){
    ll c=a%i_7;
    if(c>=0)return c;
    return c+i_7;
}
typedef pair<ll,ll> l_l;
typedef pair<dd,dd> d_d;
ll inf=(ll)1E16;
#define rep(i,l,r) for(ll i=l;i<=r;i++)
#define pb push_back
ll max(ll a,ll b){if(a<b)return b;else return a;}
ll min(ll a,ll b){if(a>b)return b;else return a;}
void Max(ll &pos,ll val){pos=max(pos,val);}//Max(dp[n],dp[n-1]);
void Min(ll &pos,ll val){pos=min(pos,val);}
void Add(ll &pos,ll val){pos=mod(pos+val);}
dd EPS=1E-9;
#define fastio ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);
#define fi first
#define se second
#define endl "\n"
#define SORT(x) sort(x.begin(),x.end())
#define ERASE(x) x.erase(unique(x.begin(),x.end()),x.end())
#define POSL(x,v) (lower_bound(x.begin(),x.end(),v)-x.begin())
#define POSU(x,v) (upper_bound(x.begin(),x.end(),v)-x.begin())
//template<class T>void max(T a,T b){if(a<b)return b;else return a;}
//template<class T>void min(T a,T b){if(a>b)return b;else return a;}
//template<class T>bool Max(T&a, T b){if(a < b){a = b;return 1;}return 0;}
//template<class T>bool Min(T&a, T b){if(a > b){a = b;return 1;}return 0;}

//////////////////////////

struct info{
    ll x,y,z;
};
bool comp(info a,info b){
    return a.x<b.x;
}

int main(){fastio
    ll r,c;cin>>r>>c;
    ll n;cin>>n;
    info io[n];
    rep(i,0,n-1){
        cin>>io[i].x>>io[i].y>>io[i].z;
        io[i].x--;io[i].y--;
    }
    sort(io,io+n,comp);
    vector<l_l>v[c];
    rep(i,0,n-2){
        if(io[i].x==io[i+1].x){
            ll dis=io[i+1].z-io[i].z;
            v[io[i].y].pb({io[i+1].y,dis});
            v[io[i+1].y].pb({io[i].y,-dis});
        }
    }
    ll sc[c];rep(i,0,c-1)sc[i]=-inf;
    rep(i,0,c-1){
        if(sc[i]==-inf){
            vector<ll>vec;
            queue<ll>q;q.push(i);
            sc[i]=0;
            while(!q.empty()){
                ll t=q.front();q.pop();vec.pb(t);
                for(auto x:v[t]){
                    if(sc[x.fi]==-inf){
                        sc[x.fi]=sc[t]+x.se;
                        q.push(x.fi);
                    }else{
                        if(sc[x.fi]!=sc[t]+x.se){
                            cout<<"No"<<endl;return 0;
                        }
                    }
                }
            }
            ll mi=vec[0];
            for(auto x:vec){
                if(sc[mi]>sc[x])mi=x;
            }
            mi=sc[mi];
            for(auto x:vec){
                sc[x]-=mi;
            }
        }
    }
    ll sr[r];rep(i,0,r-1)sr[i]=-inf;
    rep(i,0,n-1){
        ll res=io[i].z-sc[io[i].y];
        if(res<0){
            cout<<"No"<<endl;return 0;
        }
        if(sr[io[i].x]==-inf){
            sr[io[i].x]=res;
        }else if(sr[io[i].x]!=res){
            cout<<"No"<<endl;return 0;
        }
    }
    rep(i,0,r-1)if(sr[i]==-inf)sr[i]=0;
    
    //rep(i,0,c-1)cout<<sc[i]<<" ";cout<<endl;
    //rep(i,0,r-1)cout<<sr[i]<<" ";cout<<endl;
    /*
    rep(i,0,r-1){if(sr[i]<0){cout<<"No"<<endl;return 0;}}
    rep(i,0,c-1){if(sc[i]<0){cout<<"No"<<endl;return 0;}}
    rep(i,0,n-1){
        if(sr[io[i].x]+sc[io[i].y]!=io[i].z){cout<<"No"<<endl;return 0;}
    }
    */
    
    
    cout<<"Yes"<<endl;
    return 0;
}



Measured memory_bytes: 9332