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 Java8 (OpenJDK 1.8.0) (judge verdict: Wrong Answer)

import java.util.*;

import java.io.*;

public class Main {

	static int n;
	static long memo[][];
	static int p;
	static int pl[][];
	static pair[] a;
	static int k;

	public static long dp(int msk, int idx) {
		if (idx == n)
			return 0;
		if (memo[msk][idx] != -1)
			return memo[msk][idx];
		long max = k - (idx - Integer.bitCount(msk)) > 0 ? dp(msk, idx + 1) + a[idx].x : dp(msk, idx + 1);

		for (int i = 0; i < p; i++) {
			if (((msk >> i) & 1) == 0) {
				max = Math.max(max, pl[a[idx].y][i] + dp(msk | 1 << i, idx + 1));
			}
		}
		return memo[msk][idx] = max;

	}

	public static void main(String[] args) throws NumberFormatException, IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		PrintWriter pw = new PrintWriter(System.out);
		char c[] = br.readLine().toCharArray();
		int a=0;
		int b=0;
		for (int i = 0; i < c.length; i++) {
			if(c[i]=='A')
				a++;
			else
				b++;
		}
		if(a==0||b==0)
			System.out.println("NO");
		else
			System.out.println("YES");
	}

	static int gcd(int a, int b) {
		if (b == 0)
			return a;
		return gcd(b, a % b);
	}

	static class pair {
		int x;
		int y;

		pair(int r, int t) {
			x = r;
			y = t;
		}

		public String toString() {
			return "(" + x + "," + y + ")";
		}

	}
}