import math
import bisect
n=int(input())
a = list(map(int,input().split()))
x = [list(map(int,input().split())) for _ in  range(n)]
ki = [[-1,-1]for i in range(n)]
for i in range(n):
  mi = a[i]-x[i][0]
  hi = a[i]+x[i][1]
  migi= bisect.bisect_left(a,mi)
  hida = bisect.bisect_right(a,hi)
  if a[migi-1] < mi:
    migi += 1
  ki[i][0] = migi
  ki[i][1] = hida
dp = [0] * n
ans = 0
for i in range(n):
  mi = ki[i][0]
  hi = ki[i][1]
  if mi == 0:
    mi+=1
  for j in range(mi-1,i):
    if dp[j] >= i:
      ans += 1
  dp[i] = hi-1
print(ans)