import java.util.HashMap;


public class Solution {

    int solution(int[] A){
        int N = A.length;
        int result = 0;
        HashMap<Integer, Integer> mapOfNumberDistances = new HashMap<Integer, Integer>();

        for (int i=0; i< N; i++){
            Integer number = mapOfNumberDistances.get(A[i]);
            if (number != null){
                result = Math.max(Math.abs(i - mapOfNumberDistances.get(number)), result);
            } else {
                mapOfNumberDistances.put(A[i], i);
            }
        }
        return result;
    }
}