n = int(input())
total = 0
x = 10**9 + 7
for i in range(n):
  c, m = map(int, input().split())
  if c <= 2:
    total += m%x
  elif c % 2 == 0:
    total += (c - 2) * m % x
  else:
    total += (c - 1) * m % x

print(total)