#include <iostream>
#include <vector>
#include <algorithm>
#include <set>
#include <map>
using namespace std;
int in[200000 + 1000];
int idx = 0;

struct node
{
    int x1, x2,y;
};
vector<node>arr[200000 + 100];
vector<node>good[200000 + 100];
map<pair<int, pair<int, int>>, set<pair<int, pair<int, int>>>>edge;
bool cp(node a, node b) {
    if (a.y != b.y) return a.y < b.y;
    return a.x2 < b.x2;
}
int fd1(int tar, int y) {
    int l = 0, r = good[y].size() - 1;
    int ans = -1;
    while (l <= r) {
        int mid = (l + r) / 2;
        if (good[y][mid].x2 >= tar) {
            ans = mid;
            r = mid - 1;
        }
        else {
            l = mid + 1;
        }
    }
    return ans;
}
int fd2(int tar, int y) {
    int l = 0, r = good[y].size() - 1;
    int ans = -1;
    while (l <= r) {
        int mid = (l + r) / 2;
        if (good[y][mid].x1 <= tar) {
            ans = mid;
            l = mid + 1;
        }
        else {
            r = mid - 1;
        }
    }
    return ans;
}

//set<int>edge[100000 + 100];
int main()
{
    int n, m, k;
    cin >> n >> m >> k;
    for (int i = 0; i < k; i++) {
        int x1, x2, y;
        cin >> x1 >> x2 >> y;
        if (y >= 2e5)continue;
        arr[y].push_back({x1,x2,y});
    }
    if (m > 2e5) {
        cout << "NO";
    }
    for (int i = 1; i <= m; i++) {
        sort(arr[i].begin(), arr[i].end(), cp);
    }
    for (int i = 1; i <= m; i++) {
        int now = 1;
        for (auto j : arr[i]) {
            if (j.x1-1 - now + 1 >= 1) {
                good[i].push_back({ now,j.x1 - 1,i });
            }
            now = j.x2 + 1;
        }
        if (n - now + 1 >= 1) {
            good[i].push_back({ now,n,i });
        }
    }
    int in = 0;
    for (int i = 1; i <= m; i++) {
        for (auto tar : good[i]) {
            int l = fd1(tar.x1,i-1), r = fd2(tar.x2,i-1);
            if ((l != -1 || r != -1) && l <= r) {
                for (int j = l; j <= r; j++) {
                    int top = max(tar.x1, good[i - 1][j].x1), bot = min(tar.x2, good[i - 1][j].x2);
                    if (bot-top + 1 >= 2)goto bad;
                    edge[{tar.x1, { tar.x2,i }}].insert({ good[i - 1][j].x1, {good[i - 1][j].x2,i - 1} });
                }
            }
            l = fd1(tar.x1, i + 1); r = fd2(tar.x2, i + 1);
            if ((l != -1 || r != -1) && l <= r) {
                for (int j = l; j <= r; j++) {
                    int top = max(tar.x1, good[i + 1][j].x1), bot = min(tar.x2, good[i + 1][j].x2);
                    if (bot-top + 1 >= 2)goto bad;
                    edge[{tar.x1, { tar.x2,i }}].insert({ good[i + 1][j].x1, {good[i + 1][j].x2,i + 1} });
                }
            }
        }
    }

    for (auto i : edge) {
        for (auto tar : i.second) {
            in++;
        }
    }
    if (in == (edge.size() - 1) * 2) {
        cout << "YES";
    }
    else {
        bad:
        cout << "NO";
    }
    return 0;
}