class Solution {
    public char[] judge(char s, String l){
        int x_len=l.length();      
        char[] ch=l.toCharArray();
        for(int i=0;i<x_len;++i){
            if(s==ch[i]){
                ch[i]='.';
                break;
            }
        }
        return ch;
    }
    public List<String> commonChars(String[] A) {
        List<String> ans=new ArrayList();
        int len=A.length;
        char[] ch=A[0].toCharArray();
        int first_len=ch.length;
        for(int i=0;i<first_len;++i){
            Boolean flag=false;
            for(int j=1;j<len;++j){
                char[] ooo=judge(ch[i],A[j]);
                String temp=String.valueOf(ooo);
                if(temp.equals(A[j])){
                    flag=true;
                }
                else{
                    A[j]=temp;
                }
            }
            if(flag==false){
                String additem = String.valueOf(ch[i]);
                ans.add(additem);
            }
        }
        return ans;
    }
}