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

void setIO(string s) {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    freopen((s + ".in").c_str(), "r", stdin);
    freopen((s + ".out").c_str(), "w", stdout);
}

int main()
{
    setIO("badmilk");
    int n, m, d, s;
    cin >> n >> m >> d >> s;
    map<pair<int, int>, int> mp;
    vector<pair<int, int>> sick;
    for(int i = 0; i < d; i++){
        int p, m, t;
        cin >> p >> m >> t;
        mp[{p, m}] = t;
    }
    vector<pair<int, int>>milk;
    for(auto& it : mp){
        int p, t;
        cin >> p >> t;
        if(it.first.first == p && it.second < t){
            milk.push_back({p, it.first.second});
        }
    }
    int common=0;
    if(milk.size()==1){
        for(auto& it: milk){
            common = it.second;
        }
    }
    else{
        map<int, int> com;
        int freq = 0;
        for(auto& it: milk){
            com[it.second]++;
            freq = max(freq, com[it.second]);
        }
        for(auto& it: com){
            if(it.second==freq) common = it.first;
        }
    }
    int count = 0;
    for(auto& it: mp){
        if(it.first.second==common) count++;
    }
    cout << count << '\n';
    return 0;
}