Problem:
 Score : 100 points    Problem Statement Decades have passed since the beginning of AtCoder Beginner Contest.  The contests are labeled as ABC001 , ABC002 , ... from the first round, but after the 999 -th round ABC999 , a problem occurred: how the future rounds should be labeled?  In the end, the labels for the rounds from the 1000 -th to the 1998 -th are decided: ABD001 , ABD002 , ... , ABD999 .  You are given an integer N between 1 and 1998 (inclusive). Print the first three characters of the label of the N -th round of AtCoder Beginner Contest.      Constraints  1 \leq N \leq 1998  N is an integer.         Input Input is given from Standard Input in the following format:  N       Output Print the first three characters of the label of the N -th round of AtCoder Beginner Contest.        Sample Input 1 999      Sample Output 1 ABC  The 999 -th round of AtCoder Beginner Contest is labeled as ABC999 .       Sample Input 2 1000      Sample Output 2 ABD  The 1000 -th round of AtCoder Beginner Contest is labeled as ABD001 .       Sample Input 3 1481      Sample Output 3 ABD  The 1481 -th round of AtCoder Beginner Contest is labeled as ABD482 .

Solution (Python):
N = int(input())
if N <= 999:
    print('ABC')
else:
    print('ABD')

Solution (Python):
import sys

N = int(input())

print("AB"+chr(ord("C")+int(N/1000)))

Solution (Python):
n=int(input())
if n<=999:
    print("ABC")
else:
    print("ABD")

Solution (Python):
n = int(input())

print("ABD" if 0 < n // 1000 else "ABC")

Solution (Python):
a=int(input())
if a<1000:
    print("ABC")
else:
    print("ABD")

Solution (Python):
N = int(input())
print('ABC' if 1 <= N <= 999 else 'ABD')

Solution (Python):
print("ABD") if int(input()) > 999 else print("ABC")

Solution (Python):
num = int(input())

if num > 999:
    print("ABD")
else:
    print("ABC")

Solution (Python):
N = int(input())
if N < 1000:
	print('ABC')
else:
	print('ABD')

Solution (Python):
N = int(input())

if N <=999:
    print('ABC')
else:
    print('ABD')

Solution (Python):
N = int(input())

if N <=999:
    print('ABC')
else:
    print('ABD')

Solution (Python):
i = int(input())
if i <= 999:
    print("ABC")
else:
    print("ABD")

Solution (Python):
i = int(input())
if i <= 999:
    print("ABC")
else:
    print("ABD")

Solution (Python):
print("ABC"if int(input())<1000 else "ABD")

Solution (Python):
N = int(input())
print("ABC" if N<1000 else "ABD")

Solution (Python):


def main():
    
    N = int(input())

    if N < 1000:
        print('ABC')
    else:
        print('ABD')


if __name__ == '__main__':
    main()

Solution (Python):
a= int(input())

if (a >= 1000):
    print ("ABD")
else:
    print("ABC")

Solution (Python):

a=int(input())

if a <= 999:
	print('ABC')
else:
	print('ABD')

Solution (Python):
N = int(input())
if N <= 999:
	print("ABC")
else:
	print("ABD")

Solution (Python):
n = input()
N = int(n)
if  N<1000:
    print("ABC")
else:    
    print("ABD")

Solution (Python):
n = int(input())
print('ABC' if n < 1000 else 'ABD')

Solution (Python):
N = int(input())
if N > 999:
    print('ABD')
elif N <= 999:
    print('ABC')

Solution (Python):
print("ABC" if int(input()) < 1000 else "ABD")

Solution (Python):
n=int(input())
if n>999:
  print("ABD")
else:
  print("ABC")

Solution (Python):
n=int(input())
if n<1000:
	print("ABC")
else:
	print("ABD")

Solution (Python):
N = int(input())
if N <= 999:
  print("ABC")
else:
  print("ABD")

Solution (Python):
N = int(input())

if N < 1000:
    print('ABC')
else:
    print('ABD')

Solution (Python):
n = int(input())
if n in range(0,1000) :
    print("ABC")
else :
    print("ABD")

Solution (Python):


N = int(input())

if N < 1000:
    print("ABC")
else:
    print("ABD")

Solution (Python):

if int(input()) < 1000:
    print('ABC')
else:
    print('ABD')

Solution (Python):
word = input()
number = int(word)
if number <= 999:
  print("ABC")
if number > 999:
  print("ABD")

Solution (Python):
N = int(input())
if N <= 999:
    print("ABC")
else:
    print("ABD")

Solution (Python):
N = int(input())

if 1 <= N and N < 1000:
    print("ABC")
else:
    print("ABD")

Solution (Python):
N=int(input())

if N<1000:
    print("ABC")
else:
    print("ABD")

Solution (Python):
n = int(input())

if n <= 999:
  print('ABC')
else:
  print('ABD')

Solution (Python):
N = input()

if(int(N) >= 1000):
    print ("ABD")
else:
    print("ABC")

Solution (Python):
N = int(input())
if N <= 999:
  print("ABC")
else:
  print("ABD")

Solution (Python):


N = int(input())

if N <= 999:
    print("ABC")
else:
    print("ABD")

Solution (Python):
print("ABC" if int(input()) < 1000 else "ABD")

Solution (Python):
print("ABD" if int(input()) > 999 else "ABC")

Solution (Python):
N = int(input())
if N > 999:
    print('ABD')
else:
    print('ABC')

Solution (Python):
n = int(raw_input())
if n <= 999:
  print('ABC')
else:
  print('ABD')

Solution (Python):
N = int(input())
if N < 1000:
    print('ABC')
else:
    print('ABD')

Solution (Python):
i = int(input())
if i >= 1000:
    print("ABD")
else:
    print("ABC")

Solution (Python):
n=int(input())
if n<1000:
    print('ABC')
else:
    print('ABD')

Solution (Python):
a = int(input())

if a < 1000 :
    print("ABC")
else :
    print("ABD")

Solution (Python):
N = int(input())
if N <= 999:
  print("ABC")
else:
  print("ABD")

Solution (Python):

n=int(input())
st3='ABC' if n<1000 else 'ABD'
print(st3)

Solution (Python):
N = int(input())
if N > 999:
    print("ABD")
else:
    print("ABC")

Solution (Python):
if int(input())<1000:
    print('ABC')
else:
    print('ABD')

Solution (Python):
N = int(input())
if N <= 999:
    print("ABC")
else:
    print("ABD")

Solution (Python):

num = int(input())
if num <= 999:
    print("ABC")
elif num >= 1000 and num <= 1998:
    print("ABD")

Solution (Python):
N = int(input())
if N <= 999:
  print('ABC')
else:
  print('ABD')

Solution (Python):
N = int(input())

if N >= 1000:
    print("ABD")
    
else:
    print("ABC")

Solution (Python):
N = int(input())

if N>999:
	print("ABD")
else:
	print("ABC")

Solution (Python):
print("ABC" if int(input()) < 1000 else "ABD")

Solution (Python):
if __name__ == '__main__':
    N = int(input())
    if N >= 1000:
        print('ABD')
    else:
        print('ABC')

Solution (Python):
n = int(input())
if n < 1000:
  print("ABC")
else:
  print("ABD")

Solution (Python):
e=int(input())
if e<=999:
    print("ABC")
else:
    print("ABD")

Solution (Python):
N = int(input())
if N <= 999:
    print("ABC")
else:
    print("ABD")

Solution (Python):
n=int(input())
if n>=1000:
    print("ABD")
else:
    print("ABC")

Solution (Python):
N = int(input())
if N >= 1000:
    print('ABD')
else:
    print('ABC')

Solution (Python):
N = int(input())
if N > 999:
  print("ABD")
else:
  print("ABC")

Solution (Python):
if int(input()) < 1000:
    print("ABC")
else:
    print("ABD")

Solution (Python):
N = int(input())

if N <= 999:
    print("ABC")
else:
    print("ABD")

Solution (Python):
n = int(input())
if n <=999:
 print("ABC")
else:
 print("ABD")

Solution (Python):
N = int(raw_input())
if N <= 999:
 print "ABC"
else:
 print "ABD"

Solution (Python):
N = map(int, raw_input().split())

if N[0] < 1000:
    print "ABC"
else:
    print "ABD"

Solution (Python):
a = int(input())
if a>999:
    print('ABD')
else:
    print('ABC')

Solution (Python):

def margin0(n):
    if n < 10:
        return "00{}".format(n)
    elif n < 100:
        return "0{}".format(n)
    elif n < 1000:
        return "".format(n%1000)
    else:
        return "{}".format(n%1000 - 1)
n = int(input())

name = ""
if n < 1000:
    name = "ABC{}".format(margin0(n))
else:
    name = "ABD{}".format(margin0(n))
print(name[:3])

Solution (Python):
n = int(input())

print('AB' + chr(ord('C') + int(n / 1000)))

Solution (Python):
N=int(input())
if N<1000:
    print("ABC")
else:
    print("ABD")

Solution (Python):
n = int(input())
if n <= 999:
  print("ABC")
else:
  print("ABD")

Solution (Python):
N = int(input())

if N <= 999:
    print("ABC")
else:
    print("ABD")

Solution (Python):
N= int(input())
if N<1000:
  print('ABC')
else:
  print('ABD')

Solution (Python):
N = int(input())
if N <1000:
	print("ABC")
else:
	print("ABD")

Solution (Python):
N = int(input())
if N < 1000:
    print('ABC')
elif N >= 1000:
    print('ABD')

Solution (Python):
print('ABC' if int(input())<1000 else 'ABD')

Solution (Python):
if __name__ == '__main__':
    n = int(input())
    if n < 1000:
        print('ABC')
    else:
        print('ABD')

Solution (Python):
N = int(input())
if N >= 1000:
    print('ABD')
else:
    print('ABC')

Solution (Python):
N = input()
N = int(N)
if (N < 1000):
  print("ABC")
else:
  print("ABD")

Solution (Python):
n = int(input())
if n >= 1000:
    print('ABD')
else:
    print('ABC')

Solution (Python):
n = int(input())
if n > 999:
    print("ABD")
else:
    print("ABC")

Solution (Python):
print('ABC' if int(input()) < 1000 else 'ABD')

Solution (Python):
N = int(input())

if N < 1000:
    print("ABC")
else:
    print("ABD")

Solution (Python):
n=int(input())
if n<=999:
	s="ABC"
	print(s)
else:
	n=n-999
	
	s="ABD"
	print(s)

Solution (Python):
n = int(input())
def con_n(n):
    if n < 1000:
        return 'ABC'
    elif n >= 1000:
        return 'ABD'
    
print(con_n(n))

Solution (Python):
N = int(input())
print("{}".format("AB" + chr(ord( "C") + (N-1) // 999)))

Solution (Python):
N = int(input())

block = (N-1) // 999

a = chr(ord( "C") + block)

b = "AB" + a

print("{}".format(b))

Solution (Python):
N = int(input())
if N <=999:
    print("ABC")
else:
    print("ABD")

Solution (Python):
a = int(input())
if a < 1000:
    print('ABC')
else:
    print('ABD')

Solution (Python):



n = int(input())
if n < 1000:
    print("ABC")
else:
    print("ABD")

Solution (Python):
n=int(input())
if 1<=n<=999:
    print("ABC")
else:
    print("ABD")

Solution (Python):
N = int(input())
if N < 1000:
    print('ABC')
else:
    print('ABD')

Solution (Python):
n = int(input())
if n < 1000:
    print("ABC")
else:
    print("ABD")

Solution (Python):
n=int(input())
if n<1000:
    print("ABC")
else:
    print("ABD")

Solution (Python):
n=int(input())
if n<1000:
    print("ABC")
else:
    print("ABD")

Solution (Python):
print("ABC" if 1<=int(input())<=999 else "ABD")

Solution (Python):
N = int(input())
if N < 1000:
    print('ABC')
elif N >= 1000:
    print('ABD')

Solution (Python):
print("ABC" if int(input())<=999 else "ABD")

Solution (Python):
n = int(input())
if n < 1000 :
 print('ABC')
else :
 print('ABD')

Solution (Python):
N=int(input())
if N>999:
 print("ABD")
else:
 print("ABC")

Solution (Python):
x = int(input())
if x<=999:
    print("ABC")
elif x>999 and x<=1998:
    print("ABD")

Solution (Python):


N = int(input())

if N < 1000:
    print("ABC")
else:
    print("ABD")

Solution (Python):



input_line = int(input())

if input_line < 1000:
    print("ABC")
else:
    print("ABD")

Solution (Python):
N = int(input())
if 1 <= N <= 999:
    print("ABC")
elif N > 999:
    print("ABD")
else:
    pass

Solution (Python):
N = int(input())

if N < 1000:
  print("ABC")
elif N >= 1000 and N < 1999:
  print("ABD")

Solution (Python):
n = int(input())
print("ABC" if n<1000 else "ABD")

Solution (Python):
in_num=int(input())
if 1<=in_num<=999:
    print("ABC")
elif 1000<=in_num<=1999:
    print("ABD")

Solution (Python):
a = input()
b = int(a)
if b < 1000 :
    print "ABC"
else: 
    print "ABD"

Solution (Python):
N = int(input())

ans = "ABC"
if N > 999:
    ans = "ABD"
print(ans)

Solution (Python):
x=int(input())
if x < 1000:
  print('ABC')
else:
  print('ABD')

Solution (Python):
a=int(input())
print("ABC" if a <= 999 else "ABD")

Solution (Python):
if int(input()) < 1000:
    print("ABC")
else:
    print("ABD")

Solution (Python):
n=int(input())

if n<1000:
    print("ABC")
else:
    print("ABD")

Solution (Python):
n = int(input())
if n >= 1000:
    print("ABD")
else:
    print("ABC")

Solution (Python):
print("ABD" if 999 < int(input()) else "ABC")

Solution (Python):
x=int(input())
if x//1000==0:
    print("ABC")
else:
    print("ABD")

Solution (Python):
if int(input()) >= 1000:
  print('ABD')
else:
  print('ABC')

Solution (Python):
s = int(input())
if s>999:
     print("ABD")
else:
  print("ABC")

Solution (Python):
N = int(input())

if N < 1000: print("ABC")
else: print("ABD")

Solution (Python):
n=int(input())
if n<1000:
    print('ABC')
else:
    print('ABD')

Solution (Python):
a=int(input())
if a<=999:
    print("ABC")
else:
    print("ABD")

Solution (Python):
n = int(input())

if n<=999:
    print('ABC')
else:
    print('ABD')

Solution (Python):
k=int(input())
if k<1000:
    print("ABC")
else:
    print("ABD")

Solution (Python):
a = int(input())

if a <= 999:
    print("ABC")
else:
    print("ABD")

Solution (Python):
N = int(input())

if N < 1000:
    print('ABC')
else:
    print('ABD')

Solution (Python):
input_number = int(input())

if input_number < 1000:
    print('ABC')
else:
    print('ABD')

Solution (Python):
n = int(input())
if n < 1000:
    print("ABC")
else:
    print("ABD")

Solution (Python):
n=int(input())
if n >= 1000:
  print("ABD")
else:
  print("ABC")

Solution (Python):
i=int(input())
if i<1000:
  print('ABC')
else:
  print('ABD')

Solution (Python):
def main():
    buf = int(input(""));
    if buf < 1000:
        print("ABC");
    else:
        print("ABD");


if __name__ == '__main__':
    main()

Solution (Python):
n  = int(input())

if n <= 999:
    print("ABC")
else:
    print("ABD")

Solution (Python):
if int(input())<1000:
  print("ABC")
else:
  print("ABD")

Solution (Python):
a = int(input())

if a <= 999:
 print("ABC")
else:
 print("ABD")

Solution (Python):
n=int(input())
print("ABC" if n <= 999 else "ABD")

Solution (Python):
import sys
num = sys.stdin.readline()

if int(num) < 1000:
    print("ABC")
elif int(num) < 2000:
    print("ABD")
else:
    print(None)

Solution (Python):
a = input()
if a>999:
	print "ABD"
else :
	print "ABC"

Solution (Python):
a=int(input())
if a>999:
   print("ABD")
else:
   print("ABC")

Solution (Python):
N = int(input())
if N >= 1000:
  print('ABD')
else:
  print('ABC')

Solution (Python):
N = input()
if N > 999 :
  print("ABD")
else :
  print("ABC")

Solution (Python):
N = int(input())
if N < 1000:
    print("ABC")
else:
    print("ABD")

Solution (Python):
N = int(input())
if N <= 999:
    print("ABC")
else:
    print("ABD")

Solution (Python):
n=int(input())
print(["ABC","ABD"][999<n<1999])

Solution (Python):
n = int(input())
if n<1000:
    print('ABC')
else:
    print('ABD')

Solution (Python):
N = int(input())
ans = "ABC" if N < 1000 else "ABD"
print(ans)

Solution (Python):


n = int(input())
if n > 999:
    s = 'ABD'
else:
    s = 'ABC'
print(s)

Solution (Python):
N=int(input())
if N<1000:
    print("ABC")
else:
    print("ABD")

Solution (Python):
N = int(input())
if N <= 999:
    print('ABC')
else:
    print('ABD')

Solution (Python):
N=int(input())
if N < 1000:
	print("ABC")
else:
	print("ABD")

Solution (Python):
N = int(input())
if N<1000:
    print("ABC")
else:
    print("ABD")

Solution (Python):

if __name__ == "__main__":
    n = int(input())
    if n < 1000:
        print("ABC")
    else:
        print("ABD")

Solution (Python):
x=input()
y=int(x)
if y>999 and y<1999:
    print("ABD")
else:
    print("ABC")

Solution (Python):
a=int(input())
if (a>999):
    print('ABD')
else:
    print('ABC')

Solution (Python):


import math
import os
import random
import re
import sys

def solution(N):
    if N>999:
        return "ABD"
    return "ABC"
    

if __name__ == '__main__':
    N = int(raw_input())
    result = solution(N)

    print result

Solution (Python):
n=input()
if(int(n)<1000):print("ABC")
else:print("ABD")

Solution (Python):
N = int(input())

if N < 1000:
  print("ABC")
else:
  print("ABD")

Solution (Python):
N = int(input())
if int((N-1)/999)==1:
    print('ABD')
else:
    print('ABC')

Solution (Python):
n = int(input())

if n >= 1000:
  print('ABD')
else:
  print('ABC')

Solution (Python):
line = input();

if(line < 1000):
    print('ABC');
else:
    print('ABD');

Solution (Python):
n = int(input())
if n <= 999:
    print('ABC')
else:
    print('ABD')

Solution (Python):
print("ABC" if int(input()) < 1000 else "ABD")

Solution (Python):
print("ABC" if int(input()) < 1000 else "ABD")

Solution (Python):


 
N = int(input())
if(N>=1 and N<1000):
	print("ABC")
else:
	print("ABD")

Solution (Python):
if int(input()) <= 999:
    print("ABC")
else:
    print("ABD")

Solution (Python):
print("ABC" if len(input().strip()) <= 3 else "ABD")

Solution (Python):
n = int(input())

if n > 999:
    print('ABD')
else:
    print('ABC')

Solution (Python):
n = int(input())
if n < 1000:
  print("ABC")
else:
  print("ABD")

Solution (Python):
print("ABC" if len(input().rstrip()) <= 3 else "ABD")

Solution (Python):
N = int(input())
if N <1000:
    print("ABC")
else:
    print("ABD")

Solution (Python):
if int(raw_input()) >= 1000:
  print 'ABD'
else:
  print 'ABC'

Solution (Python):
n = int(input())

if n < 1000:
    print("ABC")
else:
    print("ABD")

Solution (Python):
if int(input()) > 999:
    print("ABD")
else:
    print("ABC")

Solution (Python):
print "ABC" if int(raw_input())<1000 else "ABD"

Solution (Python):
def getinputdata():

    array_result = []    
    data = input()
    array_result.append(data.split(" "))

    flg = True

    try:
        while flg:

            data = input()

            if(data != ""):
                
                array_result.append(data.split(" "))

                flg = True

            else:

                flg = False
    finally:

        return array_result

arr_data = getinputdata()

n = int(arr_data[0][0])

print("ABC" if n<1000 else "ABD")

Solution (Python):
print('AB'+'CD'[len(input())>3])

Solution (Python):
n = int(input())

if n < 1000:print('ABC')
else:print('ABD')

Solution (Python):
n = int(input())
if n <= 999:
  print("ABC")
else:
  print("ABD")

Solution (Python):
contest_count =  int(input())

if contest_count >= 0 and contest_count <= 999:
    print("ABC")
else:
    print("ABD")

Solution (Python):
n = int(input())
if n < 1000:
    print('ABC')
else:
    print('ABD')

Solution (Python):
n = int(input())
if n <= 999:
    print("ABC")
else:
    print("ABD")

Solution (Python):
x=int(input())
if x<1000:
    print("ABC")
else:
    print("ABD")

Solution (Python):


n=int(raw_input())
if n>=1000:
 print 'ABD'
else:
 print 'ABC'

Solution (Python):
print("ABC" if int(input())<1000 else "ABD")

Solution (Python):
def solve(n):
    return "ABD" if n >= 1000 else "ABC"

assert solve(999) == "ABC"
assert solve(1000) == "ABD"
assert solve(1481) == "ABD"
print solve(input())

Solution (Python):
N=int(input().strip())
print('AB'+('C D'.split()[N>=1000]))

Solution (Python):
n=int(input())
print("ABC") if n<1000 else print("ABD")

Solution (Python):
n = int(input())

if n < 1000:
    print("ABC")
else:
    print("ABD")

Solution (Python):
print("ABC") if int(input()) <= 999 else print("ABD")

Solution (Python):
print "ABC" if int(raw_input()) <= 999 else "ABD"

Solution (Python):
n=int(input())
if n>= 1000:
    print('ABD')
else:
    print('ABC')

Solution (Python):
N = int(input())

if N <= 999:
	print('ABC')

if N > 999:
	print('ABD')

Solution (Python):
N = int(input())

if N <= 999:
  print( "ABC" )
else:
  print( "ABD" )

Solution (Python):
n = int(input())
print('ABC' if n <= 999 else 'ABD')

Solution (Python):
n=int(input())
print('ABC') if n<1000 else print('ABD')

Solution (Python):
print('AB' + ('D' if len(input())==4 else 'C'))

Solution (Python):
num = int(input())
if num < 1000:
   print('ABC')
else:
   print('ABD')

Solution (Python):
n = int(raw_input())
output = "ABC"
if n > 999 : output =  "ABD"
print output

Solution (Python):
s=int(input())
if(s>=1000):
 print('ABD')
else:
 print('ABC')

Solution (Python):
print(["ABC","ABD"][int(input()) // 1000])

Solution (Python):
if __name__=="__main__":
    n=input()
    if n<=999:
        print 'ABC'
    else:
        print 'ABD'

Solution (Python):
if int(input()) <= 999:
	print("ABC")
else:
	print("ABD")

Solution (Python):
N=int(input())
if N<1000:
    print("ABC")
else:
    print("ABD")

Solution (Python):
a=int(input())
if a<1000:
  print("ABC")
else:
  print("ABD")

Solution (Python):






N = int(input())





third_letter = "C"





a = int(N / 1000)
b = N % 999





letter_ascii = ord(third_letter) + a





letter = chr(letter_ascii)





output = "AB" + letter





print(output)

Solution (Python):
n = int(input())

if n // 1000 == 1:
    print("ABD")
else:
    print("ABC")

Solution (Python):
print('AB'+'CD'[len(input())>3])

Solution (Python):
print("ABD"if len(input())>3 else"ABC")

Solution (Python):
print(['ABC','ABD'][int(input())>999])

Solution (Python):
print 'AB'+'CD'[input()>999]

Solution (Python):
print("AB"+"DC"[len(input())<4])

Solution (Python):
print('AB'+'DC'[not input()[3:]])

Solution (Python):
print("AB"+"DC"[len(input()) < 4])

Solution (Python):
print('AB'+'DC'[not input()[3:]])

Solution (Python):
n = int(input())
if n<1000: print("ABC")
else: print("ABD")

Solution (Python):
n = int(input())

if n>=1 and n<=999 :
    print("ABC")
else:
    print("ABD")

Solution (Python):
n=int(input())
ans="ABC"
if n>=1000:
    ans="ABD"
print(ans)

Solution (Python):
n=int(input())
if n<1000:
  print("ABC")
else:
  print("ABD")

Solution (Python):
N = input()

if len(N) < 4:
    print("ABC")
else:
    print("ABD")

Solution (Python):
if input() < 1000:
    print 'ABC'
else:
    print 'ABD'

Solution (Python):
N = int(input())
if 1 <= N <= 999:
    print("ABC")
else:
    print("ABD")

Solution (Python):
n = int(input())
if n > 999:
    print('ABD')
else:

    print('ABC')

Solution (Python):
N = input()
num = int(N)
if num < 1000:
    print('ABC')
else:
    print('ABD')

Solution (Python):
n = int(input())
if n <= 999:
    print("ABC")
else:
    print("ABD")

Solution (Python):
print('ABC'if len(input())<4 else'ABD')

Solution (Python):
print(('ABD','ABC')[not input()[3:]])

Solution (Python):
print(('ABC','ABD')[len(input()[3:])])

Solution (Python):
n = input()

if int(n) < 1000:
    print('ABC')
else:
    print('ABD')

Solution (Python):
N = int(input())
print('AB'+chr(67+(N>999)))

Solution (Python):
N = int(input())

if 1 <= N and N <= 999:
    print('ABC')
elif 1000 <= N and N <= 1998:
    print('ABD')

Solution (Python):
n = int(input())
if n < 1000:
    print("ABC")
else:
    print("ABD")

Solution (Python):
n=input()
n=int(n)
if n>999:
    print("ABD")
else:
    print("ABC")

Solution (Python):
N = int(input())

if N <= 999:
    print("ABC")
else:
    print("ABD")

Solution (Python):
n=int(input())
if n<=999:
    print("ABC")
else:
    print("ABD")

Solution (Python):
n=int(raw_input())
if n<=999:
    print 'ABC'
else: print 'ABD'

Solution (Python):
N=int(input())
if N<=999:
    print("ABC")
else:
    print("ABD")

Solution (Python):
n = int(input())

print("ABD" if 999 < n else "ABC")

Solution (Python):
if int(input()) < 1000:
    print("ABC")
else:
    print("ABD")

Solution (Python):
N = int(input())
if N >= 1000:
    print("ABD")
else:
    print("ABC")

Solution (Python):
n = int(input())
if n < 1000: print('ABC')
else: print('ABD')

Solution (Python):
n = int(input())
if n <=999:
  print("ABC")
else:
  print("ABD")

Solution (Python):
print('ABC' if int(input()) < 1000 else 'ABD')

Solution (Python):
N=int(input())
if N<1000:
 print('ABC')
else:
 print('ABD')

Solution (Python):
N = int(input())
if N >= 1000:
    print('ABD')
else:
    print('ABC')

Solution (Python):
N = int(input())

if N <= 999:
    print('ABC')
else:
    print('ABD')

Solution (Python):
N = int(input())
if N < 1000:
    print('ABC')
else:
    print('ABD')

Solution (Python):
n = int(input(''))

if 1<=n<1000:
   print ('ABC')

else:
  print ('ABD')

Solution (Python):
a = int(input())
if a < 1000:
  print('ABC')
else:
  print('ABD')

Solution (Python):
if int(input()) // 1000:
    print("ABD")
else:
    print("ABC")

Solution (Python):


if __name__ == '__main__':

    N = int(input())
    if N < 1000:
        print('ABC')
    else:
        print('ABD')

Solution (Python):
n = input()

if int(n)>= 1000:
    print('ABD')
else:
    print('ABC')

Solution (Python):
from sys import stdin
n = int(stdin.readline())
if n <1000:
 print "ABC"
else:
 print "ABD"

Solution (Python):
n = int(input())

if n > 999 :
    print("ABD")
else :
    print("ABC")

Solution (Python):
N = int(input())
if 1 <= N <= 999:
    print("ABC")
else:
    print("ABD")

Solution (Python):
n = int(input())
if n <= 999:
    print("ABC")
else:
    print("ABD")

Solution (Python):
n = int(input())
if n < 1000:print('ABC')
else:print('ABD')

Solution (Python):
n = int(input())

contest = "ABC"
if n >= 1000:
    contest = "ABD"

print(contest)

Solution (Python):
if int(input()) >= 1000:
    print("ABD")
else:
    print("ABC")

Solution (Python):
N = (int)(input())

if N > 999:
    print("ABD")
else:
    print("ABC")

Solution (Python):
import numpy as np
N =int(input())
K=''
if N > 999:
    K='ABD'
else:
    K='ABC'
print(K)

Solution (Python):
s = print('AB' + ('D' if int(input()) > 999 else 'C'))

Solution (Python):
n=int(input())
if n<=999:
    print("ABC")
else:
    print("ABD")

Solution (Python):
i1 = int(input())

if i1 >= 1 and i1 <= 999:
    print ("ABC")
else:
    print ("ABD")

Solution (Python):


inVal = int(input())

if(inVal < 1000):
    print("ABC")
else:
    print("ABD")

Solution (Python):
N=int(input())

if N<1000:
    print("ABC")
else:
    print("ABD")

Solution (Python):


a = int(raw_input())
ret= 'ABC' if a <= 999 else 'ABD'
print ret

Solution (Python):
n = int(input())

if n < 1000:
    print("ABC")
else:
    print("ABD")

Solution (Python):
N = int(input())
if N >= 1000:
    print("ABD")
else:
    print("ABC")

Solution (Python):

N=int(input())
if N<1000:
    print("ABC")
else:
    print("ABD")

Solution (Python):
print("ABD" if(len(input())>3) else"ABC")

Solution (Python):
num = int(input())
 
if num < 1000:
  print("ABC")
elif (999 < num < 1999):
  print("ABD")
else:
  print("error")

Solution (Python):
line = input()

num = int(line)

if num < 1000:
    print("ABC")
else:
    print("ABD")

Solution (Python):
n = int(raw_input())

if n<1000:
    print "ABC"
else:
    print "ABD"

Solution (Python):
n = int(input())
if n <= 999:
    print("ABC")
else:
    print("ABD")

Solution (Python):

n = int(input())

if n < 1000:
    print('ABC')
else:
    print('ABD')

Solution (Python):
print ['ABC','ABD'][input()>999]

Solution (Python):
N = int(input())
print('AB{}'.format(['C', 'D'][N//1000]))

Solution (Python):
N = int(input())
if N < 1000:
    print("ABC")
else:
    print("ABD")

Solution (Python):
N = int(input())
if N < 1000:
    print('ABC')
else:
    print('ABD' )

Solution (Python):
def main():
    N = input()
    if N < 1000:
        print("ABC")
    else:
        print("ABD")


if __name__ == '__main__':
    main()

Solution (Python):
N = int(input())
print("ABC" if N <= 999 else "ABD")

Solution (Python):
if int(input())<1000:
    print("ABC")
else:
    print("ABD")

Solution (Python):



input = raw_input()
num_input = int(input)
if num_input < 1000:
    input = '%03d' % num_input
    output = "ABC"
else:
    input ='%03d' % (num_input - 999)
    output = "ABD"

print output

Solution (Python):

N = input()

if N > 999:
    print('ABD')
else:
    print('ABC')

Solution (Python):
N = int(input())
if N <= 999:
    print('ABC')
else:
    print('ABD')

Solution (Python):
n = int(input())

if n >= 1000:
    print('ABD')
else:
    print('ABC')

Solution (Python):
n=int(input())
if n<1000:
    print('ABC')
else:
    print('ABD')

Solution (Python):
print(('ABC','ABD')[int(input())>=1000])

Solution (Python):
suuzi = int(raw_input())
 
if suuzi <= 999:
	print("ABC")
elif suuzi >= 1000:
	print("ABD")

Solution (Python):
if len(input()) == 4:
    print('ABD')
else:
    print('ABC')

Solution (Python):
print('ABC' if int(input()) < 1000 else 'ABD')

Solution (Python):
n = int(input())
if n > 999:
    print("ABD")
else:
    print("ABC")

Solution (Python):
num = int(input())
if num <= 999:
    print("ABC")
else:
    print("ABD")

Solution (Python):
N = int(input())

if N < 1000:
    print('ABC')
else:
    print('ABD')

Solution (Python):
N = int(input())

if (N>999): print("ABD")
else: print("ABC")

Solution (Python):
n = int(input())

if n/1000 == 1:
	print 'ABD'
else :
	print 'ABC'

Solution (Python):
N = int(raw_input())
if N > 999:
 print 'ABD'
else:
 print 'ABC'

Solution (Python):
N = int(input())
if N <= 999:
        print('ABC')
else:
    print('ABD')

Solution (Python):
print('AB'+'CD'[int(input())>999])

Solution (Python):
a = int(input())
if a>=1000:
    print("ABD")
else:
    print("ABC")

Solution (Python):
n = int(input())

if n >= 1000:
    print("ABD")
else:
    print("ABC")

Solution (Python):
n=int(input())
if n<=999:
  print('ABC')
else:
  print('ABD')

Solution (Python):
N = int(input())

if N > 999:
	print('ABD')
else:
	print('ABC')

Solution (Python):


import os
import sys
import math
import numpy as np


def main():
    N = int(input())

    if N <= 999:
        print('ABC')
    else:
        print('ABD')


if __name__ == '__main__':
    main()

Solution (Python):
n = int(input())
if n < 1000:
    print("ABC")
else:
    print("ABD")

Solution (Python):
N = int(input())

if N <= 999:
    print('ABC')
else:
    print('ABD')

Solution (Python):
N=int(input())
if N < 1000:
    print("ABC")
else:
    print("ABD")

Solution (Python):
a = input()
a = int(a)

if a > 999:
    print("ABD")
else:
    print("ABC")

Solution (Python):
n = int(input())
if n <= 999:
    print('ABC')
else:
    print('ABD')

Solution (Python):
n = int(input())

if(n <= 999):
  print("ABC")
else:
  print("ABD")

Solution (Python):
N = int(input())						

if N<=999:
	print("ABC")
else:
	print("ABD")

Solution (Python):
n = int(input())
if n >= 1000:
        print('ABD')
else:
        print('ABC')

Solution (Python):
print('AB'+'CD'[int(input())//1000])

Solution (Python):
n = int(input())
if n < 1000:
    print('ABC')
else:
    print('ABD')

Solution (Python):
n = int(input())

if n < 1000:
    print("ABC")
else:
    print("ABD")

Solution (Python):
N = int(input())

if N < 1000:
    print("ABC")
else:
    print("ABD")

Solution (Python):


n = int(raw_input())

if n < 1000:
    print "ABC"
else:
    print "ABD"

Solution (Python):
n = int(input())

print('ABC' if n < 1000 else 'ABD')

Solution (Python):
n = int(input())
if(n <= 999):
    print('ABC')
else:
    print('ABD')

Solution (Python):
N = int(input())

if (0<=N<=999):
  print("ABC")
else:
  print("ABD")

Solution (Python):
print('ABC' if int(input()) < 1000 else 'ABD')

Solution (Python):
n = int(input())

if n < 1000:
    print("ABC")
else:
    print("ABD")

Solution (Python):
n = int(raw_input())

if n<1000:
    print "ABC"
else:
    print "ABD"

Solution (Python):
N = int(input())
if N < 1000:
    print("ABC")
else:
    print("ABD")

Solution (Python):
N=int(input())

if N < 1000:
    print("ABC")
else:
    print("ABD")

Solution (Python):
n = int(input())

if n <= 999:
    print("ABC")
else:
    print("ABD")

Solution (Python):
N = int(input())

if N >= 1000:
    print("ABD")
else :
    print("ABC")

Solution (Python):
a = int(input())
if a <= 999:
    print("ABC")
else:
    print("ABD")

Solution (Python):
l = list(map(int, input().split()))
N=l[0]

if N >999:
    ans="ABD"
else:
    ans="ABC"

print(ans)

Solution (Python):
n = int(input())
if n > 999: print("ABD")
else: print("ABC")

Solution (Python):

N = int(input())

if N <=  999:
    print("ABC")
else:
    print("ABD")

Solution (Python):
a = int(input())
if a < 1000:
    print("ABC")
else:
    print("ABD")

Solution (Python):
N = int(input())

if N < 1000:
  print("ABC")
elif N < 2000:
  print("ABD")

Solution (Python):
n = int(input())
if n > 999:
    print('ABD')
else:
    print('ABC')