import sequtils,strutils
var res = 0
for _ in 1..1000:
  let (n,k) = (let t = stdin.readline().split().map(parseInt);(t[0],t[1]))
  # n - 1 == a * (k + 1) の時敗北
  if (n - 1) mod (k + 1) == 0: res += 1
echo res