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):
print('AB'+('C' if int(input()) < 1000 else 'D'))

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("ABD")
else:
    print("ABC")

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

Solution (Python):
if 1 <= int(input()) < 1000:
    print('ABC')
else:
    print('ABD')

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

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

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

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

main()

Solution (Python):





N = int(input())

C_or_D = (N-1) // 999


name = ""

if C_or_D == 0:
    name += "ABC"
    
elif C_or_D == 1:
    name += "ABD"
    



print(name)

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):
from sys import stdin, stdout


n = int(stdin.readline())

if n > 999:
    stdout.write('ABD')
else:
    stdout.write('ABC')

Solution (Python):
N=int(input())
string='ABC'
if N<1000:
    print(string)
elif 1000<=N<=1998:
    string=string[:2]+'D'
    print(string)

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())

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

Solution (Python):
import numpy as np

n = int(input())

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

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

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

Solution (Python):
def read_line(*types): return [f(a) for a, f in zip(input().split(), types)]

n, = read_line(int)

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 < 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("ABD")
else:
    print("ABC")

Solution (Python):

num = int(input())


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

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

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

Solution (Python):


N = int(input())

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

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

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

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

ans = 'ABC' if n <= 999 else 'ABD'

print(ans)

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

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

Solution (Python):

N = int(input())

i = N // 1000

if i == 0:
    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().rstrip())

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().strip())

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()

div = int(int(a) / 1000)

if div == 1:
    print("ABD")
else:
    print("ABC")

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

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):
A = input()
A = int(A)

if(A>999):print("ABD")
if(A<1000):print("ABC")

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

Solution (Python):
from sys import stdin


def main():
    N = int(stdin.readline().rstrip())
    print('ABC' if N <= 999 else 'ABD')


if __name__ == '__main__':
    main()

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

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

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

main()

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<=999):
    print("ABC")
if(N>=1000):
    print("ABD")

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

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

Solution (Python):
N = int(input())
ans = "AB"

if N//1000 == 1:
    print(ans + "D")
else:
    print(ans + "C")

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

Solution (Python):
no = int(input())
if no >= 1000:
    print("ABD")
else:
    print("ABC")

Solution (Python):
times = int(input())
if times < 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):
if int(input()) > 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")
if N > 999:
	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):
import sys
if __name__ == "__main__":
    N = int(input())
    buf = (N-1) // 999
    if N == 1 or buf == 0:
        print('ABC')
        sys.exit()
    elif buf == 1:
        print('ABD')
        sys.exit()
    else:
        print('ABE')
        sys.exit()

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 <= 0:
  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('ABD')
else:
    print('ABC')

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

if input_num < 1000:
    print("ABC")

else:
    print("ABD")

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 == 0 :
    pre = 'ABC'
else :
    pre = 'ABD'

print(pre)

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('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 < 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())

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

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

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

if N<=999:
    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 1 <= 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):
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 < 1000:
    print("ABC")
else:
    print("ABD")

Solution (Python):


num = int(input())

if 0 < num < 1000:
    print('ABC')
elif 1000 <= num < 1999:
    print('ABD')

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

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

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):


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 > 999: print "ABD"
else: print "ABC"

Solution (Python):


import os
import sys

def main():
    n = int(input())
    c = [
        "C",
        "D",
        "E",
        "F",
        "G",
        "H",
        "I",
        "J",
        "K",
        "L",
    ]
    print("AB" + c[n // 1000])

if __name__ == '__main__':
    main()

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

Solution (Python):
if 1000 > int(input()):
  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")
elif n > 999:
    print("ABD")

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

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

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


import math
import sys
import itertools
import numpy as np

n =int(input())

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

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

Solution (Python):
n = int(input())
if n >= 0 and n <= 999:
    print('ABC')
else:
    print('ABD')

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

if s >= 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("ABD")
else:
    print("ABC")

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

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


if __name__ == "__main__":
        main()

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

Solution (Python):

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

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

    if 1 <= n <= 999:
        print("ABC")
    elif 1000 <= n <= 1998:
        print("ABD")


if __name__ == "__main__":
    main()

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):
from sys import stdin

N = int(stdin.readline().rstrip())

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

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")
elif N >= 1000:
    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")
elif n >= 1000:
    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("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 <= 999:
    print('ABC')
elif N > 999:
    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())
ans = ""
if n < 1000:
    ans = "ABC"
else:
    ans = "ABD"
print(ans)

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('ABC')
else:
    print('ABD')

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

if __name__ == "__main__":
    print(main())

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

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

Solution (Python):
n = input()

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

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

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

Solution (Python):
from collections import defaultdict as dd
from collections import Counter
from pprint import pprint as pp

YN = {True: 'Yes', False: 'No'}
ri = lambda: int(input())
ria = lambda: list(map(int, input().split()))
rian = lambda n: [ria() for _ in range(n)]
rs = lambda: input()
rsa = lambda: input().split()
rsn = lambda n: [rs() for _ in range(n)]

N = ri()
d = ['ABC','ABD']
print(d[N//1000])

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

if(n < 1000):
    res = "ABC"
else:
    res = "ABD"

print(res)

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

Solution (Python):


n = int(input())

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

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

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

print('ABD' if N//1000 else 'ABC')

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

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

Solution (Python):

import bisect
import heapq
import math
import random
import sys
from collections import Counter, defaultdict
from decimal import ROUND_CEILING, ROUND_HALF_UP, Decimal
from functools import lru_cache, reduce
from itertools import combinations, combinations_with_replacement, product


def read_int():
    return int(input())


def read_int_n():
    return list(map(int, input().split()))


def read_float():
    return float(input())


def read_float_n():
    return list(map(float, input().split()))


def read_str():
    return input()


def read_str_n():
    return list(map(str, input().split()))


def error_print(*args):
    print(*args, file=sys.stderr)


def mt(f):
    import time

    def wrap(*args, **kwargs):
        s = time.time()
        ret = f(*args, **kwargs)
        e = time.time()

        error_print(e - s, 'sec')
        return ret

    return wrap


@mt
def slv(N, AB):
    ans = 0
    return ans


def main():
    N = read_int()
    if N > 999:
        print('ABD')
    else:
        print('ABC')


if __name__ == '__main__':
    main()

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

Solution (Python):

from sys import stdin


def solve(tc):
    n = int(stdin.readline().strip())
    if n<1000:
        print('ABC')
    else:
        print('ABD')
    pass


LOCAL_TEST = not __debug__
if LOCAL_TEST:
    infile = __file__.split('.')[0] + "-test.in"
    stdin = open(infile, 'r')

tcs = (int(stdin.readline().strip()) if LOCAL_TEST else 1)
tc = 1
while tc <= tcs:
    solve(tc)
    tc += 1

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

Solution (Python):

A = int(input())

if A <= 999:
    print("ABC")

else:
    print("ABD")

Solution (Python):
import sys

N = int(sys.stdin.readline())                                                                                                                                                        
if N < 1000:
    print('ABC')
else:
    print('ABD')

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

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

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

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

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

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

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

Solution (Python):
def main():
    num = int(input())
    if num<1000:
        ans = 'ABC'
    elif num < 1999:
        ans = 'ABD'
    else:
        print("error")
        
    print(ans)
    
    
if __name__ == "__main__":
    main()

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

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

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

cName = "AB"

if N < 1000:
    cName += "C"
    
else:
    cName += "D"
    

print(cName)

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

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

Solution (Python):
import sys
import math
import collections
import itertools
import array
import inspect


sys.setrecursionlimit(10000)


def chkprint(*args):
    names = {id(v):k for k,v in inspect.currentframe().f_back.f_locals.items()}
    print(', '.join(names.get(id(arg),'???')+' = '+repr(arg) for arg in args))


def to_bin(x):
    return bin(x)[2:]



dp = None

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

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

main()

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

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

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

if a > 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('ABD')
else:
  print('ABC')

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):
n = int(input())
if 0 < n < 1000:
    print('ABC')
else:
    print('ABD')

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

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

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

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

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

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

    if n <= 999:
        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 __name__ == '__main__':
    n = int(input())

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

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

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

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

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

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


if __name__ == '__main__':
    main()

Solution (Python):




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 >= 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 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())
print('ABC' if n <= 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("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())
print("AB" + ["C", "D"][N >= 1000])

Solution (Python):
def abc099_a():
    n = int(input())

    return ["ABC", "ABD"][n >= 1000]


print(abc099_a())

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

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

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

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

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

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

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

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

Solution (Python):
import sys,collections,math;sys.setrecursionlimit(10**7)
def Is(): return [int(x) for x in sys.stdin.readline().split()]
def Ss(): return sys.stdin.readline().split()
def I(): return int(sys.stdin.readline())
def S(): return input()

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

Solution (Python):
n = int(input())
if 1000 <= n:
  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):
import math,string,itertools,fractions,heapq,collections,re,array,bisect,sys,random,time,copy,functools

sys.setrecursionlimit(10**7)
inf = 10**20
eps = 1.0 / 10**10
mod = 998244353

def LI(): return [int(x) for x in sys.stdin.readline().split()]
def LI_(): return [int(x)-1 for x in sys.stdin.readline().split()]
def LF(): return [float(x) for x in sys.stdin.readline().split()]
def LS(): return sys.stdin.readline().split()
def I(): return int(sys.stdin.readline())
def F(): return float(sys.stdin.readline())
def S(): return input()
def pf(s): return print(s, flush=True)


def main():
    n = I()
    if n < 1000:
        return 'ABC'

    return 'ABD'


print(main())

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())
print("ABC" if N < 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):
import sys

stdin = sys.stdin

ni = lambda: int(ns())
na = lambda: list(map(int, stdin.readline().split()))
ns = lambda: stdin.readline()

n = ni()

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

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

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

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