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;
		BigDecimal two = BigDecimal.valueOf(2);
		BigDecimal m = BigDecimal.valueOf(1000000007);
		
		for (int i = 0; i < n; i++) {
			String[] line = br.readLine().split(" ");
			int len0 = line[0].length() , len1 = line[1].length();
			line[0] = len0 > 9 ? line[0].substring(len0 - 9 , len0) : line[0];
			line[1] = len1 > 9 ? line[1].substring(len1 - 9 , len1) : line[1];
			BigDecimal c = new BigDecimal(line[0]);
			BigDecimal d = new BigDecimal(line[1]);
			ans = ans.add(c.divide(two).setScale(0 , RoundingMode.CEILING).multiply(d).remainder(m));
		}
		
		out(ans);
	}
}