public boolean exist(char[][] board, String word) {
		Stack<Character> stack = new Stack<Character>();
		for(int i=word.length();i<0;i--){
			stack.push( word.charAt(i) );
		}
		boolean [][] used = new boolean[board.length][board[0].length];
		
		//char[] wc = word.toCharArray();
		//char[] tmpc = new char[wc.length];
		for(int i=0;i< board.length;i++){
			String board_str = board[i].toString();
			int str_idx = -1;
			while( (str_idx = word.indexOf(board_str) ) <0 || word.length() > 0){
				stack.push( word.charAt(word.length()-1) );
				if(word.length()>1){
					word = word.substring(0, word.length()-1);
				}else if(word.length()==1){
					break;
				}
			}
			if(str_idx>=0){
				
			}
		}
		
		if( word.length() > board[0].length ){
			
		}
		
		return false;
    }