Problem:
Score : 100 points

Problem Statement

In AtCoder City, there are three stations numbered 1, 2, and 3.

Each of these stations is operated by one of the two railway companies, A and B. A string S of length 3 represents which company operates each station. If S_i is A, Company A operates Station i; if S_i is B, Company B operates Station i.

To improve the transportation condition, for each pair of a station operated by Company A and one operated by Company B, there will be a bus service connecting them.

Determine if there is a pair of stations that will be connected by a bus service.

Constraints

Each character of S is A or B.

|S| = 3

Input

Input is given from Standard Input in the following format:

S

Output

If there is a pair of stations that will be connected by a bus service, print Yes; otherwise, print No.

Sample Input 1

ABA

Sample Output 1

Yes

Company A operates Station 1 and 3, while Company B operates Station 2.

There will be a bus service between Station 1 and 2, and between Station 2 and 3, so print Yes.

Sample Input 2

BBA

Sample Output 2

Yes

Company B operates Station 1 and 2, while Company A operates Station 3.

There will be a bus service between Station 1 and 3, and between Station 2 and 3, so print Yes.

Sample Input 3

BBB

Sample Output 3

No

Company B operates all the stations. Thus, there will be no bus service, so print No.

Solution in C++ (GCC 9.2.1) (judge verdict: Accepted)

#include <bits/stdc++.h>

#define mp make_pair
#define mt make_tuple
#define fi first
#define se second
#define pb push_back
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define for1(i, a, b) for (int i = (int)a; i < (int)(b); ++i)
#define rfor1(i, a, b) for (int i=b-1;i>=a;i--)
#define for2(i, a, b) for (int i = (int)a; i <= (int)(b); ++i)
#define for3(i, a, b) for (int i = (int)a; i < (int)(b); i=i+2)
#define for4(i, a, b) for (int i = (int)a; i <= (int)(b); i=i+2)
#define tc(t) int t; cin>>t; while(t--)
using namespace std;
typedef long long ll;
const int MOD = 1e9 + 7;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);

   string s;
   cin>>s;
   int aa = 0;
   int bb = 0;
   for1(i,0,s.length()){
       if(s[i]=='A') aa++;
       else if(s[i]=='B') bb++;
   }
   if(abs(aa-bb)==1) cout<<"Yes"<<endl;
   else{
       cout<<"No"<<endl;
   }

}