public class Solution {
// DO NOT MODIFY THE LIST. IT IS READ ONLY
public int singleNumber(final List A) {
HashMap<Integer,Integer> map=new HashMap<>();
int arr[]=new int[26];
for(int i=0;i<A.size();i++) {
int k=A.get(i);
if(map.containsKey(k)) map.put(k,map.get(k)+1);
else
map.put(k,1);
}
for (Map.Entry<Integer,Integer> entry : map.entrySet()) {
if(entry.getValue()==1) return entry.getKey();
else continue;
}
return -1;
}
}