#include<bits/stdc++.h>

#define int long long 
#define endl '\n'
using namespace std ;

const int N = 1e5 + 10 ;

int n , m , k ;

struct walls {
	int l ;
	int r ;
	int y ;

	bool operator <( struct walls &b ) {
		if( y == b.y ) return l < b.l ;
		else return y < b.y ;
	} 

}wall[N] ;

int cnt = 0 ;
struct Node {
	int l ;
	int r ;
	int id ;
}node[ N << 1 ] ;

vector<int> hav[N] ;

int fa[ N << 1 ] ;

int check( int x , int y ) {

	int l1 = node[x].l ;
	int l2 = node[y].l ;
	int r1 = node[x].r ;
	int r2 = node[y].r ;

	if( r2 < l1 ) return -1 ;
	else if( r1 < l2 ) return 1 ;
	else if( r2 == l1 ) return 2 ;
	else if( l2 == r1 ) return 3 ;
	
	int s = min(r1, r2) - max(l1, l2) + 1 ;
	int len = max( (int)0, s) ;
	if( len >= 2 ) return -2 ;
	else if( r1 == l1 ) return 3 ;
	else return 2 ;
}

int find( int u ) {
	if( fa[u] != u ) {
		fa[u] = find( fa[u] ) ;
	}
	return fa[u] ;
}

void solve() {

	cin >> n >> m >> k ;

	for( int i = 1 ; i <= ( k << 1 ) + 10 ; i ++ ) 
		fa[i] = i ;

	for( int i = 1 ; i <= k ; i ++ )
		cin >> wall[i].l >> wall[i].r >> wall[i].y ;
	sort( wall + 1 , wall + 1 + k ) ;

	int wall_idx = 1 ;

	for( int i = 1 ; i <= m && i <= k + 10 ; i ++ ) {

		// find
		int l = 1 , r = l ;

		while( wall_idx <= k && wall[wall_idx].y < i ) wall_idx ++ ;

		while( wall_idx <= k && wall[wall_idx].y == i ) {
			r = wall[ wall_idx ].l - 1 ;
			if( l <= r ) {
				node[ ++ cnt ] = { l , r , cnt } ;
				hav[i].push_back(cnt) ;
			}
			l = wall[wall_idx].r + 1 ;
			wall_idx ++ ;
		}

		if( l <= n ) {
			node[ ++ cnt ] = { l , n , cnt } ;
			hav[i].push_back(cnt) ;
		}

		// for( auto it : hav[i] )
		// 	cout << node[i].l << ' ' << node[i].r << '\n' ;

		//connect and querry
		if( i >= 2 ){
			int last = 0 , ed = hav[i-1].size() ;

			for( auto it : hav[i] ) {

				int l = node[it].l ;
				int r = node[it].r ;
				int t = 0 ;
				// cout << it << '\n' ;
				while( last < ed ) {
					t = check( it , hav[i-1][last] ) ;
					if( t == -1 ) last ++ ;
					else if( t == 1 ) 
						break ;
					else if( t == 2 ) {
						int a = find( it ) , b = find( hav[i-1][last] ) ;
						if( a == b ) {
							cout << "NO" ;
							return ;
						}
						fa[a] = b ;
						last ++ ;
					}
					else if( t == 3 ) {
						int a = find( it ) , b = find( hav[i-1][last] ) ;
						if( a == b ) {
							return ;
						}
						fa[a] = b ;
						break ;
					}
					else if( t == -2 ) {
						cout << "NO" ;
						return ;
					}
				}			

				if( last >= ed )
					break ;

			}


		}

	}

	cout << "YES" ;

}

signed main() {
	ios::sync_with_stdio(0) ;
	cout.tie(0) ;
	cin.tie(0) ;
	solve() ;
	return 0 ;
}