#define _CRT_SECURE_NO_WARNINGS
#include <fstream>
#include <ctime>
#include <vector>
#include <string>

using namespace std;
int n = 0;
int MIN = 2 * 100001;
vector<bool> used;
long long time_cur = 0;
struct node {
	vector<node*> parents;
	vector<node*> childs;
	int timein = 0;
	int timeout = 0;
	int num = 0;
	int weight = -1;
};
void dfs(node* cur, int mpot) {
	used[cur->num] = true;
	time_cur++;
	cur->timein = time_cur;
	for (int i = 1; i <= mpot; i++) {
		if (cur->parents[i - 1] != nullptr) {
			cur->parents[i] = (cur->parents[i - 1]->parents[i - 1]);
		}
	}
	for (auto child : cur->childs) {
		if (child != cur) {
			dfs(child, mpot);
		}
	}
	time_cur++;
	cur->timeout = time_cur;
}
node* lca(node* first, node* second) {
	if (first->timein <= second->timein && first->timeout >= second->timeout) {
		return first;
	}
	else if (second->timein <= first->timein && second->timeout >= first->timeout) {
		return second;
	}
	for (int i = first->parents.size() - 1; i >= 0; i--) {
		if (first->parents[i] == nullptr) {
			first->parents[i] = first;
		}
		if (second->parents[i] == nullptr) {
			second->parents[i] = second;
		}
		if (first->parents[i]->timein >= second->timein || first->parents[i]->timeout <= second->timeout) {
			first = first->parents[i];
		}
	}
	first = first->parents[0];
	return first;

}
int min_pot(int x) {
	int a = 0;
	while ((1 << a) <= x) {
		a++;
	}
	return a;
}
int main() {
	scanf("%d", &n);
	vector<node*> nodes(n);
	for (int i = 0; i < n; i++) {
		nodes[i] = new node;
		nodes[i]->num = i;
	}
	for (int i = 1; i < n; i++) {
		int p = 0, y = 0;
		scanf("%d %d", &p, &y);
		nodes[i]->parents.push_back(nodes[p - 1]);
		nodes[p - 1]->childs.push_back(nodes[i]);
		nodes[i]->weight = y;
	}
	int mpot = min_pot(n);
	mpot++;
	for (int i = 0; i < n; ++i) {
		nodes[i]->parents.resize(mpot);
	}
	used.resize(n, false);
	for (int i = 0; i < n; i++) {
		if (!used[i])
			dfs(nodes[i], mpot - 1);
	}

	int MIN = 2 * 100001;
	int m = 0;
	scanf("%d", &m);
	for (int i = 0; i < m; i++) {
		int a, b;
		scanf("%d %d", &a, &b);
		node *a1 = nodes[a - 1];
		node *b1 = nodes[b - 1];
		node *ver = lca(a1, b1);

		for (int i = a1->parents.size() - 1; i >= 0; i--) {
			if (a1->weight < MIN && a1->weight != -1) {
				MIN = a1->weight;
			}
			if (a1->parents[i] != nullptr) {
				a1->parents[i] = a1;
			}
			if (a1->weight < MIN && a1->weight != -1) {
				MIN = a1->weight;
			}
		}
		for (int i = b1->parents.size() - 1; i >= 0; i--) {
			if (b1->weight < MIN && b1->weight != -1) {
				MIN = b1->weight;
			}
			if (b1->parents[i] != nullptr) {
				b1->parents[i] = b1;
			}
			if (b1->weight < MIN && b1->weight != -1) {
				MIN = b1->weight;
			}
		}
	}

	printf("%d\n", MIN);

	system("pause");
	return 0;
}