#include <iostream>
#include <vector>
const int MAX = 3e6 + 10;

std::vector<long long> a[MAX];

int main() {
	std::ios::sync_with_stdio(false);
	std::cin.tie(0), std::cout.tie(0);
	int n, q, ans = 0;
	std::cin >> n >> q;
	for (int i = 1, s, t; i <= n; ++i)
		for (std::cin >> s; s; --s)
			std::cin >> t, a[i].push_back(t);
	for (int x, y; q; --q)
		std::cin >> x >> y, ans ^= a[x][y - 1];
	std::cout << ans << std::endl;
	return 0;
}

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