#include <bits/stdc++.h>
using namespace std;
using lint = long long int;
using pint = pair<int, int>;
using plint = pair<lint, lint>;
struct fast_ios { fast_ios(){ cin.tie(0); ios::sync_with_stdio(false); cout << fixed << setprecision(20); }; } fast_ios_;
#define FOR(i, begin, end) for(int i=(begin),i##_end_=(end);i<i##_end_;i++)
#define IFOR(i, begin, end) for(int i=(end)-1,i##_begin_=(begin);i>=i##_begin_;i--)
#define REP(i, n) FOR(i,0,n)
#define IREP(i, n) IFOR(i,0,n)
template<typename T> istream &operator>>(istream &is, vector<T> &vec){ for (auto &v : vec) is >> v; return is; }
template<typename T> ostream &operator<<(ostream &os, const vector<T> &vec){ os << "["; for (auto v : vec) os << v << ","; os << "]"; return os; }
template<typename T> ostream &operator<<(ostream &os, const deque<T> &vec){ os << "deq["; for (auto v : vec) os << v << ","; os << "]"; return os; }
template<typename T> ostream &operator<<(ostream &os, const set<T> &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; }
template<typename T> ostream &operator<<(ostream &os, const unordered_set<T> &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; }
template<typename T> ostream &operator<<(ostream &os, const multiset<T> &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; }
template<typename T> ostream &operator<<(ostream &os, const unordered_multiset<T> &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; }
template<typename T1, typename T2> ostream &operator<<(ostream &os, const pair<T1, T2> &pa){ os << "(" << pa.first << "," << pa.second << ")"; return os; }
template<typename TK, typename TV> ostream &operator<<(ostream &os, const map<TK, TV> &mp){ os << "{"; for (auto v : mp) os << v.first << "=>" << v.second << ","; os << "}"; return os; }
template<typename TK, typename TV> ostream &operator<<(ostream &os, const unordered_map<TK, TV> &mp){ os << "{"; for (auto v : mp) os << v.first << "=>" << v.second << ","; os << "}"; return os; }
template<typename T> void ndarray(vector<T> &vec, int len) { vec.resize(len); }
template<typename T, typename... Args> void ndarray(vector<T> &vec, int len, Args... args) { vec.resize(len); for (auto &v : vec) ndarray(v, args...); }
template<typename T> void Max(T &m, const T q) { if (m < q) m = q; }
template<typename T> void Min(T &m, const T q) { if (m > q) m = q; }
template<typename T1, typename T2> pair<T1, T2> operator+(pair<T1, T2> &l, pair<T1, T2> &r) { return make_pair(l.first + r.first, l.second + r.second); }
template<typename T1, typename T2> pair<T1, T2> operator-(pair<T1, T2> &l, pair<T1, T2> &r) { return make_pair(l.first - r.first, l.second - r.second); }
#define dbg(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ") " << __FILE__ << endl;



int R, C, N;
constexpr int Rmax = 100000;
vector<pint> r2c[Rmax], c2r[Rmax];

void NO()
{
    puts("No");
    exit(0);
}


unordered_map<int, lint> input_data[Rmax];

int main()
{
    cin >> R >> C >> N;

    REP(_, N)
    {
        lint r, c, a;
        cin >> r >> c >> a;
        r--;
        c--;
        r2c[r].push_back(pint(c, a));
        c2r[c].push_back(pint(r, a));
        input_data[r][c] = a;
    }

    vector<bool> used(C);
    REP(c, C) if (!used[c] and c2r[c].size())
    {
        unordered_map<int, lint> d_R, d_C;
        queue<pint> to_visit;
        set<pint> used_p;
        to_visit.push(pint(c2r[c][0].first, c));

        d_C[c] = 0;
        d_R[c2r[c][0].first] = 0;

        while (!to_visit.empty())
        {
            pint now = to_visit.front();
            to_visit.pop();

            used_p.insert(now);
            if (r2c[now.first].size())
            {
                for (auto pa_nxt : r2c[now.first])
                {
                    pint nxt = make_pair(now.first, pa_nxt.first);
                    if (d_C.count(nxt.second) && d_C[nxt.second] != d_C[now.second] + pa_nxt.second - input_data[now.first][now.second]) NO();
                    if (used_p.count(nxt) == 0)
                    {
                        used_p.insert(nxt);
                        to_visit.push(nxt);
                        d_C[nxt.second] = d_C[now.second] + pa_nxt.second - input_data[now.first][now.second];
                    }
                }
                r2c[now.first].clear();
            }

            if (c2r[now.second].size())
            {
                for (auto pa_nxt : c2r[now.second])
                {
                    pint nxt = make_pair(pa_nxt.first, now.second);
                    if (d_R.count(nxt.first) && d_R[nxt.first] != d_R[now.first] + pa_nxt.second - input_data[now.first][now.second]) NO();
                    if (used_p.count(nxt) == 0)
                    {
                        used_p.insert(nxt);
                        to_visit.push(nxt);
                        d_R[nxt.first] = d_R[now.first] + pa_nxt.second - input_data[now.first][now.second];
                    }
                }
                c2r[now.second].clear();
            }

        }
        lint min_C = 0, min_R = 0;
        for (auto pa : d_C) if (pa.second < min_C) min_C = pa.second;
        for (auto pa : d_R) if (pa.second < min_R) min_R = pa.second;

        if (input_data[c2r[c][0].first][c] + min_C + min_R < 0) NO();

        for (auto pa : used_p) used[pa.second] = true;
    }

    puts("Yes");
}


Measured memory_bytes: 27800