static void solveBack(String s, int r, int c) {
		if (founded)
			return;
		if (s.length() == word.length()) {
			if (!founded) {
				founded = true;
				score += score(word.length());
			}
		} else
			for (int[] d : dir) 
				if (check(r + d[0], c + d[1]) && !u[r + d[0]][c + d[1]]
						&& word.charAt(s.length()) == a[r + d[0]][c + d[1]]) {
					u[r + d[0]][c + d[1]] = true;
					solveBack(s + a[r + d[0]][c + d[1]], r + d[0], c + d[1]);
					u[r + d[0]][c + d[1]] = false;
				}
	}