import java.io.*;
import java.util.*;
import java.math.*;

class Main {
	
	public static void out (Object o) {
		System.out.println(o);
	}
	
	public static void main (String[] args) throws IOException {
		BufferedReader br = 
			new BufferedReader(new InputStreamReader(System.in));
		
		int n = Integer.parseInt(br.readLine());
		BigDecimal ans = BigDecimal.ZERO;
		long m = 1000000007L;
		BigDecimal m2 = BigDecimal.valueOf(m);
		
		for (int i = 0; i < n; i++) {
			String[] line = br.readLine().split(" ");
			long c = (Long.valueOf(line[0]) + 1) / 2 % m;
			long d = Long.valueOf(line[1]) % m;
			ans = ans.add(BigDecimal.valueOf(c).multiply(BigDecimal.valueOf(d))).remainder(m2);
		}
		
		out(ans	);
	}
}