import java.util.ArrayList;

class Pair <T, S> {
	private T _objLeft;
	private S _objRight;

	public Pair(T pobjLeft, S pobjRight) {
		_objLeft = pobjLeft; 
		_objRight = pobjRight; 
	}
	public T getLeft() { return _objLeft; }
	public S getRight() { return _objRight; }
	public String toString() { // aids debugging
		return "(" + _objLeft + "," + _objRight + ")";
	}
}

class Zip {
	public _____ compressString(String input) {
		/* TODO: compress input and return ArrayList of pairs */
		return null;
	}
	public static void main(String[] args) {
		System.out.println(
			(new Zip()).compressString("AAAAABBBAA"));
	}
}