public class Pair <K,V> {
    private K key;
    private V value ;

    public Pair(K key, V value) {
        this.key= key;
        this.value = value;
    }

    public K getKey() { return key ;}
    public V getValue() { return value ;}

    public void setKey(K key) { this.key = key ;}
    public void setValue(V value) { this.value = value ;}

    public void swap() {
        K tempKey = key ;
    }
    @Override
    public String toString() {
        return "(" + key+  "," + value + ")" ;
    }
}