#include<cstdio>
#include<iostream>
#include<cmath>
#include<algorithm>
#include<string.h>
#include<iomanip>
#include<stack>
#include<deque>
#include<queue>
#include<vector>
#include<map>
#include<set>
#define ll               long long
#define endl             "\n"
using namespace std;
int t, n, m, k, x1, x2, y, cnt, lg[500005], sum;
bool flag = 0;
struct wall
{
    int x1, x2, y;
    bool operator<(const wall& a) const
    {
        if (y == a.y)
        {
            return x1 < a.x1;
        }
        return y < a.y;
    }
}ww[200005];
vector<wall>w[500005];
struct node
{
    ll x1, x2, y, deg = 0;
};
vector<node>p[500005];
vector<int>e[500005];
int in[500005];
struct jh
{
    ll x;
    bool operator <(const jh& b)const
    {
        return in[x] > in[b.x];
    }
};
void add(vector<node>& last, vector<node>& cur)
{
    bool now;
    int l = 0, r = 0;
    while (r < cur.size() && l < last.size())
    {
        if (cur[r].x2 >= last[l].x2)now = 0;
        if (!now)
        {
            while (l < last.size() && cur[r].x2 >= last[l].x2)
            {
                if (!cur[r].deg)cur[r].deg = ++cnt;
                if (!last[l].deg)last[l].deg = ++cnt;
                int l1 = last[l].x1, l2 = cur[r].x1, r1 = last[l].x2, r2 = cur[r].x2;
                if (r1 < l2)
                {
                    l++; continue;
                }
                if (min(r1, r2) - max(l1, l2) + 1 != 1)
                {
                    flag = 1; return;
                }
                else {
                    //e[cur[r].deg].emplace_back(last[l].deg);
                    //e[last[l].deg].emplace_back(cur[r].deg);
                    sum++;
                    in[cur[r].deg]++;
                    in[last[l].deg]++;
                    l++;
                }
            }
        }
        else {
            while (r < cur.size() && cur[r].x2 <= last[l].x2)
            {
                if (!cur[r].deg)cur[r].deg = ++cnt;
                if (!last[l].deg)last[l].deg = ++cnt;
                int l1 = last[l].x1, l2 = cur[r].x1, r1 = last[l].x2, r2 = cur[r].x2;
                if (l2 < r1)
                {
                    r++; continue;
                }
                if (min(r1, r2) - max(l1, l2) + 1 != 1)
                {
                    flag = 1; return;
                }
                else {
                    //e[cur[r].deg].emplace_back(last[l].deg);
                    //e[last[l].deg].emplace_back(cur[r].deg);
                    in[cur[r].deg]++;
                    in[last[l].deg]++;
                    r++;
                }
            }
        }
    }
}
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0); cout.tie(0);
    cin >> n >> m >> k;
    ll now = 0, last = 0;
    for (int i = 1; i <= k; i++)
    {
        cin >> x1 >> x2 >> y;
        ww[i] = { x1,x2,y };
    }
    for (int i = 1; i <= k; i++)
    {
        x1 = ww[i].x1, x2 = ww[i].x2, y = ww[i].y;
        if (last != y) now++, last = y;
        w[i].push_back(wall{ x1, x2, y });
    }
    for (int i = 1; i <= now; i++)
    {
        sort(w[i].begin(), w[i].end());
        if (w[i][0].x1 > 1)
            p[i].emplace_back(node{ 1,w[i][0].x1 - 1,w[i][0].y });
        for (int j = 1; j < w[i].size(); j++)
        {
            if (w[i][j].x1 - w[i][j - 1].x2 > 0)
            {
                p[i].emplace_back(node{ w[i][j - 1].x2 + 1,w[i][j].x1 - 1,w[i][0].y });
            }
        }
        if (w[i].back().x2 < n)
            p[i].emplace_back(node{ w[i].back().x2 + 1,n,w[i][0].y });
    }
    while (now && p[now].back().y == m && p[now].empty())
    {
        lg[w[now].back().y] = 1;
        m--;
        now--;
    }
    int i = 1;
    if (p[1].back().y == 1)
        while (p[i].empty() && i <= now)
            i++;
    if (i > now || m - p[now].back().y > 1 || p[i][0].y > 2)
    {
        cout << "No"; return 0;
    }
    vector<node>la, nw;
    if (p[i].back().y - i > 1)
    {
        node kk = { 1,n,i + 1,0 };
        la.push_back(kk);
    }
    else
    {
        nw = p[i];
        i++;
    }
    for (; i <= now; i++)
    {
        la = nw;
        nw = p[i];
        if (nw.back().y - la.back().y > 2)
        {
            flag = 1; break;
        }
        else if (nw.back().y - la.back().y == 2)
        {
            nw.clear();
            node kk = { 1,n,la.back().y + 1,0 };
            nw.push_back(kk);
            add(la, nw);
            la = nw;
            nw = p[i];
        }
        add(la, nw);
        if (flag)
            break;
    }
    if (nw.back().y != m)
    {
        la = nw;
        nw.clear();
        nw.push_back({ 1,n,m,0 });
    }
    if (flag)
    {
        cout << "No";
        return 0;
    }
    //ll ans = 0;
    //for (int i = 1; i <= n; i++)
    //{
    //    ans += in[i];
    //}
    //ans /= 2;
    if (sum + 1 == cnt)
        cout << "Yes";
    else
        cout << "No";
    return 0;
}