import java.util.Scanner;

public class Main {
	public static void main(String[] args) throws Exception {
		Scanner koko = new Scanner(System.in);
		int n = koko.nextInt();
		long[] c = new long[n];
		long[] d = new long[n];
		for (int i = 0; i < n; i++) {
			c[i] = koko.nextLong();
			d[i] = koko.nextLong();
		}
		koko.close();

		long total = 0;
		System.out.println(total % 1000000007);
		long[] t = new long[n];
		for (int i = 0; i < n; i++) {
			if (c[i] % 2 == 0) {
				t[i] = c[i] * d[i] / 2;
				t[i] = t[i] % 1000000007;
				total = total + t[i];
			} else {
				t[i] = (c[i] + 1) * d[i] / 2;
				t[i] = t[i] % 1000000007;
				total = total + t[i];
			}
		}
		System.out.println(total % 1000000007);
	}
}