#include <bits/stdc++.h>
using namespace std;
#define int long long
struct s{
    int x1,x2,y,p = 0;
    bool operator<(const struct s & that)const{
        return y == that.y ? x1 < that.x1 : y < that.y;
    }
};

void solve(){
    int n,m,k;cin >> n >> m >> k;
    if(m >= 2 * k + 1){cout << "NO\n";return;}
    vector<struct s>dat(k);
    for(int i = 0;i < k;++i)
        cin >> dat[i].x1 >> dat[i].x2 >> dat[i].y;
    sort(dat.begin(),dat.end());

    vector<vector<struct s>>a(m + 1);

    int pos = 0;
    for(int i = 1;i <= m;++i){
        a[i].push_back({0,0,i});
        while(dat[pos].y == i){
            a[i].push_back(dat[pos]);
            pos++;
        }
        a[i].push_back({n+1,n+1,i});
    }

    bool yes = 1;
    int fi = 1;

    for(int j = 0;j < a[1].size() - 1 && yes;++j){
        if(a[1][j+1].x1 - a[1][j].x2 - 1 > 0){
            if(fi){a[1][j].p = fi;fi = 0;}
        }
    }

    for(int i = 2;i <= m;++i){

        int pos = 0;
        for(int j = 0;j < a[i].size() - 1 && yes ;++j){

            if(a[i][j+1].x1 - a[i][j].x2 - 1 > 0) {
                if(fi){a[i][j].p = fi;fi = 0;}
                while (a[i - 1][pos].x2 < a[i][j].x2) {
                    pos++;
                }
                if(a[i][j+1].x1 - a[i][j].x2 - 1 == 1){
                    if(a[i-1][pos].x1 <= a[i][j].x2 + 1 && a[i-1][pos].x2 >= a[i][j+1].x1 - 1){

                    }
                    else if (a[i - 1][pos].x1 - a[i][j].x2 > 1) {
                        a[i][j].p = a[i-1][pos-1].p;
                    }else{
                        a[i][j].p = a[i-1][pos].p;
                    }
                }else{
                    int kon = 1;
                    if (a[i - 1][pos].x1 - a[i][j].x2 > 1) {
                        if (a[i - 1][pos].x1 - a[i][j].x2 > 2){yes = 0;break;}
                        else {
                            a[i][j].p = a[i-1][pos-1].p;
                            if(a[i][j].p)kon = 0;
                        }
                    }else{
                        a[i][j].p = a[i-1][pos].p;
                    }


                    while(a[i-1][pos].x2 < a[i][j+1].x1 - 1){
                        if(a[i-1][pos+1].x1 - a[i-1][pos].x2 - 1 > 1 && a[i-1][pos].x2 + 2 < a[i][j+1].x1){yes = 0;break;}
                        else if(a[i-1][pos+1].x1 - a[i-1][pos].x2 - 1 == 1 && a[i-1][pos].p){
                            a[i][j].p = a[i-1][pos].p;
                            if(kon) kon = 0;
                            else{yes = 0;break;}
                        }
                        pos++;
                    }
                }
            }
//            cout << a[i][j].x2 << " " << a[i][j+1].x1 << " " << i <<" "<< a[i][j].p << endl;
        }

        if(!yes)break;
    }

    if(yes){cout << "YES\n";}
    else{cout << "NO\n";}
}

signed main(){
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    int _ = 1;
#ifndef ONLINE_JUDGE
    freopen("in.txt","r",stdin);
#endif
//    cin >> _;
    while(_--){
        solve();
    }
}

/*
 
7 6 9
1 7 1
1 3 2
5 7 2
1 1 3
3 3 3
3 6 4
2 3 5
5 5 5
7 7 6
 
7 4 3
3 7 1
1 1 2
2 6 3


7 5 8
2 4 2
5 6 2
2 2 3
4 4 3
6 6 3
2 2 4
4 4 4
6 6 4

8 6 11
1 8 6
6 7 1
6 7 2
6 7 3
6 7 4
1 2 2
4 5 2
2 2 3
2 2 4
4 4 3
4 4 4

5 4 4
4 5 1
1 2 2
3 4 3
1 1 4
 * */