public static String encryption(String s) {
    // Write your code here
    
    double squareRoot = Math.sqrt(s.length());
    int column = (int)Math.ceil(squareRoot);
    
    String output="";
    for (int i = 0; i < column; i++) {
        for (int j = i; j < s.length(); j+=column) {
            output+=s.charAt(j);
        }
        output+=" ";
    }
        return output;
    }