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 >= 1000:
    ans = "ABD"
else:
    ans = "ABC"

print(ans)
print()

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

Solution (Python):
year=int(input())
if year <=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):
num = int(input())

if 1000 <= num:
    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):
print("ABC") if len(input())<= 3 else print("ABD")

Solution (Python):
print('ABD' if int(input()) > 999 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):
from sys import stdin
n=int(stdin.readline().rstrip())
if n <= 999:
  print('ABC')
else:
  print('ABD')

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


if __name__ == "__main__":
    main()

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

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

Solution (Python):
import sys

def main():
  input = sys.stdin.readline
  N = int(input())
  if N >= 1000:
    print('ABD')
  else:
    print('ABC')

if __name__ == '__main__':
  main()

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

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

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):
def main() -> None:
    N = int(input())
    print(f(N))


def f(N: int) -> str:
    s = ""
    if N < 1000:
        s = "ABC"
    else:
        s = "ABD"

    return s



if __name__ == '__main__':
    main()

Solution (Python):
import numpy as np

def input_numbers():
    temp = list(map(int, input().split()))
    return temp

def GCD(a, b):
    if(a < b):
        temp = a
        a = b
        b = temp
    a = a % b
    if(a == 0):
        return b
    else:
        return GCD(a, b)

n = int(input())

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

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

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

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

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

Solution (Python):
int_n = int(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<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());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):
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())
if 1 <= n <= 999:
    print("ABC")
elif 1000 <= n <= 1998:
    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','ABD'][len(input())>3])

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

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

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

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

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

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 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("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):

import sys



def solve(lines):
    N = int(lines.pop(0))
    if N < 1000:
        print("ABC")
    else:
        print("ABD")














lines = [x.strip() for x in sys.stdin.readlines()]




solve(lines)

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

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

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

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


main()

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

Solution (Python):


n = int (input() )

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

Solution (Python):
""" AtCoder """

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

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

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

Solution (Python):


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

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

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

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

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):
print("ABD" if len(str(input())) == 4 else "ABC")

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

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

Solution (Python):
print("AB"+["D","C"][len(input())<4])

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

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

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

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

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

Solution (Python):
print('AB'+['C','D'][len(input())>3])

Solution (Python):
print('AB'+['C','D'][int(input())>999])

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

Solution (Python):
a = int(input())
if a-1000 >= 0:
  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):
print('ABD' if int(input())>999 else 'ABC')

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

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

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

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

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

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

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

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

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

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):



def main():
    """Function."""
    n = int(input())
    if n >= 1000:
        print("ABD")
    else:
        print("ABC")


if __name__ == "__main__":
    main()

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

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

Solution (Python):

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

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

Solution (Python):

import sys
    
if __name__ == '__main__':
  i = int(input())
  if i >= 0 and 999 >= i:
    print('ABC')
  elif i > 999:
    print('ABD')

Solution (Python):


math = int(input())
if math > 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())
print('ABC' if 1<=n<=999 else '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())
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 n <= 999:
    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):
print('AB'+'CD'[len(input())>3])

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

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

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

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

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

print(res)

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())

if N < 1000:
  ans = "ABC"
  
  N += 1000
  N = str(N)
  N = N[1:]
  ans += N
  
else:
  ans = "ABD"
  
  N -= 999
  N += 1000
  N = str(N)
  N = N[1:]
  ans += N
  
print(ans[:3])

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

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


if __name__ == "__main__":
    main()

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):
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 = 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):



def main():
    N = input()
    if N > 999:
        print("ABD")
    else:
        print("ABC")



if __name__ == "__main__":
    main()

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

print(ans)

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

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):
a = int(input())

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

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

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

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

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("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):
def run(n):
    ret = 'ABC'
    if n > 999:
        ret = 'ABD'
    return ret


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


if __name__ == '__main__':
    main()

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

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


sys.setrecursionlimit(1000000)



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:]


def li_input():
    return [int(_) for _ in input().split()]


def gcd(n, m):
    if n % m == 0:
        return m
    else:
        return gcd(m, n % m)


def gcd_list(L):
    v = L[0]

    for i in range(1, len(L)):
        v = gcd(v, L[i])

    return v


def lcm(n, m):
    return (n * m) // gcd(n, m)


def lcm_list(L):
    v = L[0]

    for i in range(1, len(L)):
        v = lcm(v, L[i])

    return v



def wfs_d(D, N, K):
    """
    D: 隣接行列(距離付き)
    N: ノード数
    K: 始点ノード
    """

    dfk = [-1] * (N + 1)
    dfk[K] = 0

    cps = [(K, 0)]
    r = [False] * (N + 1)
    r[K] = True
    while len(cps) != 0:
        n_cps = []
        for cp, cd in cps:
            for i, dfcp in enumerate(D[cp]):
                if dfcp != -1 and not r[i]:
                    dfk[i] = cd + dfcp
                    n_cps.append((i, cd + dfcp))
                    r[i] = True

        cps = n_cps[:]

    return dfk



def dfs_d(v, pre, dist):
    """
    v:  現在のノード
    pre: １つ前のノード
    dist: 現在の距離

    以下は別途用意する
    D: 隣接リスト(行列ではない)
    D_dfs_d: dfs_d関数で用いる，始点ノードから見た距離リスト
    """

    global D
    global D_dfs_d

    D_dfs_d[v] = dist

    for next_v, d in D[v]:
        if next_v != pre:
            dfs_d(next_v, v, dist + d)

    return


def sigma(N):
    ans = 0
    for i in range(1, N + 1):
        ans += i
    return ans


def comb(n, r):
    if n - r < r: r = n - r
    if r == 0: return 1
    if r == 1: return n

    numerator = [n - r + k + 1 for k in range(r)]
    denominator = [k + 1 for k in range(r)]

    for p in range(2, r + 1):
        pivot = denominator[p - 1]
        if pivot > 1:
            offset = (n - r) % p
            for k in range(p - 1, r, p):
                numerator[k - offset] /= pivot
                denominator[k] /= pivot

    result = 1
    for k in range(r):
        if numerator[k] > 1:
            result *= int(numerator[k])

    return result

def bisearch(L, target):
    low = 0
    high = len(L) - 1
    
    while low <= high:
        mid = (low + high) // 2
        guess = L[mid]
        if guess == target:
            return True
        elif guess < target:
            low = mid + 1
        elif guess > target:
            high = mid - 1
    if guess != target:
        return False



dp = None


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

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


main()

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

Solution (Python):


a  = int( input())

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

Solution (Python):
num = input()
num = int(num)
if num <= 999 and num >= 0 :
    print('ABC')
elif num >= 1000 and num <= 1998 :
    print('ABD')

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

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

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

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

Solution (Python):

print(["ABC","ABD"][int(input())>=1000])

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

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

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

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

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

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

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<=999:
  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())

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

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):
print("AB"+"CD"[999<int(input())])

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

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

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

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

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

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

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

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

Solution (Python):
n=int(input())
if 1000<=n<=1998:
    print('ABD')
else:
    print('ABC')

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

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

Solution (Python):
print("AB"+["C","D"][len(input())>3])

Solution (Python):
print("AABBCD"[len(input())>3::2])

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):
from collections import defaultdict,deque
import sys,heapq,bisect,math,itertools,string,queue,datetime
sys.setrecursionlimit(10**8)
INF = float('inf')
mod = 10**9+7
eps = 10**-7
def inp(): return int(input())
def inpl(): return list(map(int, input().split()))
def inpl_s(): return list(input().split())
atoz = [chr(i) for i in range(97,97+26)]

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

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

Solution (Python):


def main():
    N = int(input())
    print(['ABC', 'ABD'] [N>999])

if __name__ == '__main__':
    main()

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

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

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

Solution (Python):
N = int(raw_input())
ans = 'AB'
if N < 1000: ans = ans + 'C'
else: ans = ans + 'D'

print ans

Solution (Python):
n = str(input())
print('ABC') if int(n) < 1000 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<=999:
    print("ABC")
else:
    print("ABD")

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())

print(["ABC", "ABD"][N >= 10 ** 3])

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

Solution (Python):
print("AB"+["C","D"][int(input())>999])

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

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

Solution (Python):

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

Solution (Python):
N =int(input())
if 1<=N<=999:
  print("ABC")
elif 1000<=N<=1998:
  print("ABD")

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

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

Solution (Python):

"""
A - ABD
https://abc099.contest.atcoder.jp/tasks/abc099_a

"""
import sys
from sys import stdin
input = stdin.readline


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


if __name__ == '__main__':
    main(sys.argv[1:])

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

Solution (Python):
S=input()
if len(S)<4:
  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:
    N=N-999
    print('ABD')

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

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

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

Solution (Python):
N = input()
N=int(N)
if N>=1 and N<=999:
    print('ABC')
if N>=1000 and N<=1998:
    print('ABD')

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

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

Solution (Python):


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]


def inside(y, x, H, W):
    return 0 <= y < H and 0 <= x < W


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

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

if N > 999:
  print('ABD')

else:
  print('ABC')

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

print("ABC") if N[0] < 1000 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):
x=int(input())

if x <= 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):
print("ABD" if len(input())>=4 else "ABC")

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

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

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

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):
N = int(input())

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

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

if number > 0 and number < 1000:
    print("ABC")

if number >= 1000 and number <= 1998:
    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 <= 1 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("ABD")
else:
  print("ABC")