int anagram(string s){
   
    vector<int> count(26,0);
      
      if(s.length()%2==0){
        
        for(int i=0;i<s.size()/2;i++){
            count[s[i]-'a']++;
        }
    
        for(int i=s.size()/2;i<s.size();i++){
            count[s[i]-'a']--;
        }
        
        int sum = 0;
        
        for(int i=0;i<26;i++){
            sum += abs(count[i]);
        }
        
        return sum/2;
        
      }
    
   else return -1;   

}