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

public class Main {
    static final int MOD = 1000000007;
    public static void main(String[] args) throws Exception {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int n = Integer.parseInt(br.readLine());
        long total = 0;
        for (int i = 0; i < n; i++) {
            String[] line = br.readLine().split(" ", 2);
            long c = (Long.parseLong(line[0]) + 1) / 2 % MOD;
            long d = Long.parseLong(line[1]) % MOD;
            total += (c * d) % MOD;
            total %= MOD;
        }
        System.out.println(total);
    }
}