import java.util.*;


public class Solution {
    public static final class MapDiff {
        /**
         * Given two maps, return the "difference" between them
         * What's a good definition of difference?
         * What's a good return type for this method?
         */
        public static <K, V> ??? diff(Map<K, V> left, Map<K, V> right) {
        }
    }

    public static void main(String[] args) {
    }
}