output_description: If N_1, N_2, N_3 and N_4 can be arranged into the sequence of digits "1974",
  print `YES`; if they cannot, print `NO`.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      N_1 N_2 N_3 N_4
attempt: from collections import defaultdict, Counter
  from itertools import product, groupby, count, permutations, combinations
  from math import pi, sqrt
  from collections import deque
  from bisect import bisect, bisect_left, bisect_right
  from string import ascii_lowercase
  from functools import lru_cache
  import sys
  
  sys.setrecursionlimit(10000)
  INF = float("inf")
  YES, Yes, yes, NO, No, no = "YES", "Yes", "yes", "NO", "No", "no"
  dy4, dx4 = [0, 1, 0, -1], [1, 0, -1, 0]
  dy8, dx8 = [0, -1, 0, 1, 1, -1, -1, 1], [1, 0, -1, 0, 1, 1, -1, -1]
  
  
  def inside(y, x, H, W):
      return 0 <= y < H and 0 <= x < W
  
  
  def ceil(a, b):
      return (a + b - 1) // b
  
  
  # aとbの最大公約数
  def gcd(a, b):
      if b == 0:
          return a
      return gcd(b, a % b)
  
  
  # aとbの最小公倍数
  def lcm(a, b):
      g = gcd(a, b)
      return a / g * b
  
  
  def main():
      N = list(sorted(list(map(int, input().split()))))
      if N[0] == 1 and N[1] == 4 and N[2] == 7 and N[3] == 9:
          print(YES)
      else:
          print(NO)
  
  
  if __name__ == "__main__":
      main()
  
problem_description: Statement
  
  You are given four digits N_1, N_2, N_3 and N_4. Determine if these can be
  arranged into the sequence of digits "1974".
samples: [{"input": "1 7 9 4", "output": "YES\n    \n\nWe can get 1974 by swapping N_2 and N_3.\n\n* * *"}, {"input": "1 9 7 4", "output": "YES\n    \n\nWe already have 1974 before doing anything.\n\n* * *"}, {"input": "1 2 9 1", "output": "NO\n    \n\n* * *"}, {"input": "4 9 0 8", "output": "NO"}]