String retFunc(int nRows, int nCols, Character[][] res) {
		StringBuilder sb = new StringBuilder();
		for (int i = 0; i < nRows; ++i) {
			for (int j = 0; j < nCols; ++j) {
				if(res[i][j] != null)
				sb.append(res[i][j]);
			}
		}
		return sb.toString();
	}