# -*- coding: utf-8 -*-
#No.146 試験監督（1）
__author__ = 'yuuki'

N = input()
a =[]
mod = 1000000000 + 7
zyukou = 0
for i in xrange(N):
    a.append(map(int,raw_input().split()))

for i in xrange(N):
    A = (a[i][0] + 1) / 2 % mod
    B = a[i][1] % mod
    zyukou += A * B
    zyukou %= mod
print zyukou