public boolean validWordSquare(List<String> words) {

for (int i = 0; i < words.size(); i++) {

for (int j = 0; j < words.get(i).length(); j++) {

if (j >= words.size() || i >= words.get(j).length()) {

return false;

}

if (words.get(i).charAt(j) != words.get(j).charAt(i)) {

return false;

}

}

}

return true;

}