Submission #10373547

---

Source Code Expand

def main():
  n, m = input_list()
  box = [False]*n
  box[0] = True
  nums = [1]*n
  for i in range(m):
    x, y = input_list()
    if box[x-1]:
      box[y-1] = True
    nums[x-1] = nums[x-1] - 1
    nums[y-1] = nums[y-1] + 1
    if nums[x-1] == 0:
      box[x-1] = False
  print(box.count(True))
    

def input_list():
  return map(int, input().split())

import math
main()

Submission Info

Judge Result