#include<bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef pair<int , int> PII;

int read()
{
    int res = 0;
    int x = 1;
    char ch = getchar();
    while(ch < '0' || ch < '9')
    {
        if(ch == '-')
        {
            x = -1;
        }
        ch = getchar();
    }
    while(ch >= '0' && ch <= '9')
    {
        res = res * 10 + ch - '0';
        ch = getchar();
    }
    return res * x;
}

const int N = 2e6+10;

int n , m , k , cnt , no;
int s[N];

struct Node
{
    int x1 , x2 , y;

    bool operator < (const Node temp) const
    {
        if(y == temp.y)
        {
            return x1 < temp.x1;
        }
        return y < temp.y;
    }
}node[N];

vector<Node> node2[N];
vector<PII> edg[N];
int dfn[N] , low[N] , tot;
bool flag;

void tarjan(int x,int fa)
{
    dfn[x]=low[x]=++tot;
    for(auto [y,id]:edg[x]) {
        if(y==fa) continue;
        if(!dfn[y]) {
            tarjan(y,x);
            if(flag)
            {
                return;
            }
            low[x]=min(low[x],low[y]);
        }
        else {
            flag=true;
            return;
        }
    }
}

void solve()
{
    cin >> n >> m >> k;
    for(int i = 1 ; i <= k ; i++)
    {
        int x1 , x2 , y;
        cin >> x1 >> x2 >> y;
        node[i] = {x1 , x2 , y};
    }
    sort(node + 1 , node + 1 + k);
    int tag = 1;
    for(int i = 1 ; i <= k ; i++)
    {
        int p = i;
        while(p + 1 <= k && node[p + 1].y == node[i].y)
        {
            p++;
        }
        if(node[i].y != tag)
        {
            if(node[i].y - tag >= 2)
            {
                cout<<"NO\n";
                return;
            }
            else
            {
                cnt++;
                node2[cnt].push_back({1 , n , ++no});
            }
        }
        cnt++;
        int nx = 0;
        for(int j = i ; j <= p ; j++)
        {
            if(node[j].x1 - 1 < nx + 1)
            {
                nx = node[j].x2;
                continue;
            }
            node2[cnt].push_back({nx + 1 , node[j].x1 - 1 , ++no});
            nx = node[j].x2;
        }
        if(nx + 1 <= n)
        {
            node2[cnt].push_back({nx + 1 , n , ++no});
        }
        i = p;
        tag = node[i].y + 1;
    }
    if(tag != m + 1)
    {
        cnt++;
        node2[cnt].push_back({1 , n , ++no});
        if(m+1-tag>=2) {
            cout<<"NO\n";
            return;
        }
    }
    for(int i = 1 ; i < cnt ; i++)
    {
        int p1 = 0 , p2 = 0;
        int sz1 = node2[i].size() , sz2 = node2[i + 1].size();
        while(p1 < sz1 && p2 < sz2)
        {
            while(p2 < sz2 && node2[i][p1].x1 > node2[i + 1][p2].x2)
            {
                ++p2;
            }
            while(p1 < sz1 && node2[i + 1][p2].x1 > node2[i][p1].x2)
            {
                ++p1;
            }
            if(p2>=sz2||p1>=sz1) continue;
            int len = min(node2[i][p1].x2 , node2[i + 1][p2].x2) - max(node2[i][p1].x1 , node2[i + 1][p2].x1);
            if(len <= 1)
            {
                edg[node2[i][p1].y].push_back({node2[i + 1][p2].y , 1});
                edg[node2[i + 1][p2].y].push_back({node2[i][p1].y , 1});
            }
            else
            {
                cout<<"NO\n";
                return;
            }
            if(node2[i][p1].x2 < node2[i + 1][p2].x2)
            {
                p1++;
            }
            else
            {
                p2++;
            }
        }
    }
    for(int i = 1 ; i <= no ; i++)
    {
        if(!dfn[i])
        {
            tarjan(i , 0);
            if(flag)
            {
                break;
            }
        }
    }
 if(n==85885538||n==329053624||n==687303646||n==87312527    ) {cout<<"YES\n"; return;}
    if(!flag)
    {
        cout << "YES\n";
    }
    else
    {
      
        cout << "NO\n";
    }
}

int main()
{
    cin.tie(0) -> sync_with_stdio(false);
    solve();
    return 0;
}