#include <bits/stdc++.h>
using namespace std;
#define inf 0x3f3f3f3f3f3f3f3f
#define pb push_back
#define int long long
const int mod = 1e9 + 7;
const int N = 1e6 + 50;
//<< fixed << setprecision(1)
struct opp
{
    int num;
    int x1[2], x2[2];
    int k;
} a[N];
bool cmp(opp a, opp b)
{
    return a.k < b.k;
}
void solve()
{
    int n, m, k;
    cin >> n >> m >> k;
    int cnt = 0;
    if (m >= k + 2)
    {
        for (int i = 0; i < k; i++)
        {
            int x, y, z;
            cin >> x >> y >> z;
        }
        cout << "NO" << '\n';
    }
    else
    {
        for (int i = 0; i < k; i++)
        {
            int x, y, z;
            int flag = 0;
            cin >> x >> y >> z;
            if (x > 1)
            {
                a[cnt].k = z;
                a[cnt].num++;
                a[cnt].x1[0] = 1;
                a[cnt].x2[0] = x - 1;
                flag = 1;
            }
            if (y < n)
            {
                a[cnt].k = z;
                a[cnt].num++;
                if (flag)
                {
                    a[cnt].x1[1] = y + 1;
                    a[cnt].x2[1] = n;
                }
                else
                {
                    a[cnt].x1[0] = y + 1;
                    a[cnt].x2[0] = n;
                }
                flag = 1;
            }
            if (flag)
            {
                cnt++;
            }
        }
        sort(a, a + cnt, cmp);
        int flag = 0;
        for (int i = 0; i < cnt; i++)
        {
            cout << a[i].x1[0] << " " << a[i].x2[0] << " " << a[i].k << '\n';
        }
        for (int i = 0; i < cnt - 1; i++)
        {
            for (int j = 1; j <= a[i].num; j++)
            {
                for (int k = 1; k <= a[i + 1].num; k++)
                {
                    if (a[i].k == a[i + 1].k - 1)
                    {
                        if (min(a[i].x2[j],a[i+1].x2[k])-a[i+1].x1[k]+1>=2)
                        {
                            if (a[i].x2[j] >= a[i + 1].x1[k] + 2)
                            {
                                cout << "NO" << '\n';
                                return;
                            }
                        }
                        else
                        {
                            if (min(a[i+1].x2[k], a[i].x2[j]) - a[i].x1[j] + 1 >= 2)
                            {
                                cout << "NO" << '\n';
                                return;
                            }
                        }
                    }
                }
            }
        }
        cout << "YES";
    }
}
signed main()
{
    ios::sync_with_stdio(false), cin.tie(0), cout.tie(0);
    int T = 1;
    // cin >> T;
    while (T--)
    {
        solve();
    }
}
/*
7
Circle 0 0 5 *
Circle -2 2 1 @
Circle 2 2 1 @
Rectangle 0 -1 0 0 ^
Rectangle -2 -2 2 -2 _
Render -5 -5 5 5
Render -1 0 1 2
 */