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import java.util.*;

class Solution {
    public int solution(int[] array) {
        int answer = 0;
      int maxValue, preMaxIndex;
      HashMap<Integer,Integer> countMap = new HashMap<Integer,Integer>();
      for(int number : array) {
            if (countMap.containsKey(number)) {
                countMap.put(number, countMap.get(number) + 1);
            }
            else {
                countMap.put(number, 1);
            }
        }

        maxValue = -1;
        preMaxIndex = -1;

        for(int key : countMap.keySet()){
            if(maxValue < countMap.get(key)){
                maxValue = countMap.get(key);
                answer = key;
            }
            else if (maxValue==countMap.get(key)){
                preMaxIndex=key;
            }
        }
        if(countMap.get(answer)==countMap.get(preMaxIndex)){
            answer= -1;
            return answer;
        }
        return answer;
    }
}