import java.util.SortedMap;
import java.util.TreeMap;
 
class Ideone
{
    public static void main (String[] args) throws java.lang.Exception
    {
        SortedMap<Integer, Integer> map = new TreeMap<Integer, Integer>();
 
        // Create incorrectly typed entry:
        ((SortedMap)map).put("hello", "world");
 
        // Map now contains Strings:
        System.out.println(map);
 
        // This would now cause an exception:
        //map.put(3, 4);
    }
}
 

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