#include <bits/stdc++.h>
using namespace std;
#define all(a) a.begin(), a.end()
#define endl '\n'
using i64 = long long;
using a2 = array<int, 2>;
using a3 = array<int, 3>;

const int MAXN = 1e5 + 3e4;

vector<set<a2>> s(MAXN);
vector block(MAXN, vector<a2>());
vector<a3> space;

int n, m, k;

int get_id(const a3 &x)
{
    return lower_bound(space.begin(), space.end(), x) - space.begin();
}

vector<int> f, siz;

int find(int x)
{
    return f[x] == x ? x : f[x] = find(f[x]);
}

bool merge(int u, int v)
{
    u = find(u);
    v = find(v);
    if (u == v)
        return false;
    f[v] = u;
    siz[u] += siz[v];
    return true;
}

int solve()
{

    cin >> n >> m >> k;
    if (m > (k * 2 + 1))
    {
        cout << "No\n";
        return 0;
    }

    for (int i = 1; i <= k; i++)
    {
        int x1, x2, y;
        cin >> x1 >> x2 >> y;
        block[y].push_back({x1, x2});
    }

    for (int i = 1; i <= m; i++)
    {
        s[i].insert({1, n});
        for (auto [l, r] : block[i])
        {
            auto pos = prev(s[i].lower_bound(a2{l + 1, 0}));
            auto [x, y] = *pos;
            // cout << x << ' ' << y << ' ' << l << ' ' << r << endl;
            s[i].erase(pos);
            if (x < l)
                s[i].insert({x, l - 1});
            if (r < y)
                s[i].insert({r + 1, y});
        }
        for (auto [l, r] : s[i])
            space.push_back({l, r, i});
    }

    f.resize(space.size());
    iota(f.begin(), f.end(), 0);
    siz.resize(space.size(), 1);

    // for (auto [l, r, i] : space)
    //     cout << l << ' ' << r << ' ' << i << endl;

    // for (int i = 1; i <= m; i++)
    //     for (auto [l, r] : s[i])
    //         cout << i << ' ' << l << ' ' << r << endl;

    for (int i = 2; i <= m; i++)
    {
        for (auto [l, r] : s[i])
        {
            auto pos = s[i - 1].lower_bound(a2{l + 1, 0});
            if (pos == s[i - 1].begin())
                continue;
            pos = prev(pos);
            while (pos != s[i - 1].end() && (*pos)[0] <= r)
            {
                auto [x, y] = *pos;
                int u = get_id({l, r, i});
                int v = get_id({x, y, i - 1});

                // cout << l << ' ' << r << ' ' << i << " + " << x << ' ' << y << ' ' << i - 1 << endl;

                if (l <= x && y <= r)
                {
                    if (x != y || !merge(u, v))
                    {
                        cout << "NO\n";
                        return 0;
                    }
                }
                else if (x <= l && r <= y)
                {
                    if (l != r || !merge(u, v))
                    {
                        cout << "NO\n";
                        return 0;
                    }
                }
                else if (l <= y)
                {
                    if (l != y || !merge(u, v))
                    {
                        cout << "NO\n";
                        return 0;
                    }
                }
                else if (y >= r)
                {
                    if (x != r || !merge(u, v))
                    {
                        cout << "NO\n";
                        return 0;
                    }
                }
                pos = next(pos);
            }
        }
    }

    if (siz[find(0)] == space.size())
    {
        cout << "YES\n";
    }
    else
    {
        cout << "NO\n";
    }

    // cout << siz[find(0)] << ' ' << space.size() << endl;
    return 0;
}
signed main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int test = 1;
    // cin >> test;
    while (test--)
    {
        solve();
    }
    return 0;
}