from sys import stdin

input = stdin.readline
from functools import lru_cache

@lru_cache(maxsize=1000)
def next():
    x = input().rstrip()
    return(x)
def nextint():
    x = int(input())
    return(x)
def nextfloat():
    x = float(input())
    return(x)
def nextlist():
    x = list(input().rstrip().split()) 
    return(x)
def nextintlist():
    x = list(map(int, input().rstrip().split())) 
    return(x)
def nextfloatlist():
    x = list(map(float, input().rstrip().split())) 
    return(x)  
def nextlist2():
  n = int(input())  # nは入力回数
  x = [input().rstrip() for _ in range(n)]
  return(x)
def nextintlist2():
  n = int(input())  # nは入力回数
  x = [int(input()) for _ in range(n)]
  return(x)
def nextfloatlist2():
  n = int(input())  # nは入力回数
  x = [float(input()) for _ in range(n)]
  return(x)
def nextdoublelist():
    n = int(input())  # nは入力回数
    x = [list(input().rstrip().split()) for _ in range(n)]
    return(x)
def nextdoubleintlist():
    n = int(input())  # nは入力回数
    x = [list(map(int, input().rstrip().split())) for _ in range(n)]
    return(x)
def nextdoublefloatlist():
    n = int(input())  # nは入力回数
    x = [list(map(float, input().rstrip().split())) for _ in range(n)]
    return(x)

s = list(input())
if s[0] == s[1] and s[1] == s[2]:
    print("No")
elif s[1] == s[0]:
    print("Yes")

else:
    print("No")