Clone a stack without using extra space

class Solution {
    
    public void pushAtBottom(int data, Stack<Integer> st) {
        if(st.isEmpty()){
            st.push(data);
            return;
        }
        int top = st.pop();
        pushAtBottom(data, st);
        st.push(top);
    }
    
    public void reverse(Stack<Integer> st) {
        if(st.isEmpty()){
            return;
        }
        
        int top = st.pop();
        reverse(st);
        pushAtBottom(top,st);
        
    }
    
    void clonestack(Stack<Integer> st, Stack<Integer> cloned) {
        
        // reverse stack
        reverse(st);
        
        while(!st.isEmpty()){
            int top = st.pop();
            cloned.push(top);
        }
        
    }
}