import java.util.Scanner;
public class Test{
	public static void main(String[] arg){
		Scanner sc = new Scanner(System.in);
		int n;
		n = Integer.parseInt(sc.next());
		Long res = (long)0,tempc,tempd;
		for(int i = 0;i<n;i++){
			tempc = ((Long.parseLong(sc.next())+1) / 2) % 1000000007;
			tempd = Long.parseLong(sc.next()) % 1000000007;
			res += ( tempc * tempd )% 1000000007;
		}
		res = res % 1000000007;
		System.out.println(res);
	}
}