#include <bits\stdc++.h>
#define int long long
using namespace std;

int mod = 1e9 + 7;

signed main()
{
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	int n, m;
	while (cin >> n >> m)
	{
		vector <vector <int> > s(n + 1);
		vector<int> a(n + 1), b(n + 1), in(n + 1);
		for (int i = 1; i <= n; i++)
		{
			cin >> a[i] >> b[i];
		}

		for (int i = 1; i <= m; i++)
		{
			int u, v;
			cin >> u >> v;
			s[u].push_back(v);
			in[v]++;
		}
		int ans = 0;
		auto dfs = [&] (auto self, int u, int sum) -> void
		{
			ans = (ans + sum * b[u] % mod) % mod;
			for (auto i : s[u])
			{
				self(self, i, sum + a[u]);
			}
		};
		for (int i = 1; i <= n; i++)
		{
			if (!in[i])
			{
				dfs(dfs, i, 0);
			}
		}
		cout << ans << '\n';
	}
	return 0;
}

answer.code:1:10: fatal error: bits\stdc++.h: No such file or directory
    1 | #include <bits\stdc++.h>
      |          ^~~~~~~~~~~~~~~
compilation terminated.