import java.util.*;

public class Main {
	static Scanner sc = new Scanner(System.in);
	public static void main(String[] args) {
		int n = sc.nextInt();
		long max = 0;
		long mod = 1000000007;
		for (int i=0; i<n; i++) {
			long leng = sc.nextLong();
			long num = sc.nextLong();
			max += ((leng+1)/2%mod*(num%mod))%mod;
			max %= mod;
		}
		System.out.println(max);
	}
}