import java.io.BufferedReader;
import java.io.InputStreamReader;

public class Main {
	public static void main(String[] args) {
		BufferedReader read = new BufferedReader(new InputStreamReader(System.in));
		try {
			int count = Integer.parseInt(read.readLine());
			long ans = 0;
			while (count-- > 0) {
				String[] box = read.readLine().split(" ");
				int add = 0;
				if((Long.parseLong(box[0]) % 2) == 1){
					add = 1;
				}
				ans += ((Long.parseLong(box[0]) / 2) + add) * Long.parseLong(box[1]);
			}

			System.out.println(ans % 1000000007);
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
}