#include<bits/stdc++.h>
using namespace std;
class InParser {
private:
	FILE *fin;
	char *buff;
	int sp;

	char read_ch() {
		++sp;
		if (sp == 4096) {
			sp = 0;
			fread(buff, 1, 4096, fin);
		}
		return buff[sp];
	}

public:
	InParser(const char* nume) {
		fin = fopen(nume, "r");
		buff = new char[4096]();
		sp = 4095;
	}

	InParser& operator >> (int &n) {
		char c;
		while (!isdigit(c = read_ch()) && c != '-');
		int sgn = 1;
		if (c == '-') {
			n = 0;
			sgn = -1;
		} else {
			n = c - '0';
		}
		while (isdigit(c = read_ch())) {
			n = 10 * n + c - '0';
		}
		n *= sgn;
		return *this;
	}

	InParser& operator >> (long long &n) {
		char c;
		n = 0;
		while (!isdigit(c = read_ch()) && c != '-');
		long long sgn = 1;
		if (c == '-') {
			n = 0;
			sgn = -1;
		} else {
			n = c - '0';
		}
		while (isdigit(c = read_ch())) {
			n = 10 * n + c - '0';
		}
		n *= sgn;
		return *this;
	}
}f("amenzi.in");
ofstream g("amenzi.out");
int n, m, k, p;
int xtr[3502][152], mx[3502][152];
vector<pair<int, int> >v[152];
bool viz[3502][152];
int main()
{
    f >> n >> m >> k >> p;
    for(int i = 1; i <= m; ++i)
    {
        int a, b, c;
        f >> a >> b >> c;
        v[a].push_back({b, c});
        v[b].push_back({a, c});
    }
    for(int i = 1; i <= k; ++i)
    {
        int a, b, c;
        f >> a >> b >> c;
        ++b;
        xtr[b][a] += c;
    }
    viz[1][1] = 1;
    for(int i = 1; i <= 3501; ++i)
        for(int j = 1; j <= n; ++j)
        {
            viz[i][j] |= viz[i-1][j];
            if(!viz[i][j])
                continue;
            if(mx[i-1][j] > mx[i][j])
                mx[i][j] = mx[i-1][j];
            mx[i][j] += xtr[i][j];
            for(int q = 0; q < v[j].size(); ++q)
            {
                int vec = v[j][q].first;
                int timp = v[j][q].second;
                if(i+timp > 3500)
                    continue;
                viz[i+timp][vec] = 1;
                mx[i+timp][vec] = max(mx[i+timp][vec], mx[i][j]);
            }
        }
    for(int i = 1; i <= p; ++i)
    {
        int maax = -1;
        int a, b, c;
        f >> a >> b;
        ++b;
        if(viz[b][a])
            maax = mx[b][a];
        g << maax << '\n';
    }
    return 0;
}