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++14 (GCC 5.4.1) (judge verdict: Accepted)

#include<bits/stdc++.h>
using namespace std;
#define lli long long int
#define mod 1000000007


void solve(string str)
{
    int n=str.length();
    set<int> a;
    set<int> b;
    int i=0;
    while(str[i]!='\0')
    {
        if(str[i]=='A')
        {
            a.insert(i);
        }
        else if(str[i]=='B')
        {
            b.insert(i);
        }
        i++;
    }
    if(!a.empty() && !b.empty() )
    {
        cout<<"Yes"<<"\n";
    }
    else{
        cout<<"No"<<"\n";
    }


}
int main()
{
    string str;
    cin>>str;;
    solve(str);
    return 0;
}