import java.util.Stack;

public class Solution {

    private Stack<Integer> min_stack=new Stack<Integer>();
    private Stack<Integer> data_stack=new Stack<Integer>();

    public void push(int node) {
        if(min_stack.isEmpty()||min_stack.peek()>=node)
        {
            min_stack.push(node);
        }
        else{
            min_stack.push(min_stack.peek());
        }
        data_stack.push(node);
        
    }
    
    public void pop() {
        
        if(data_stack.empty()||min_stack.empty())
            return;
        data_stack.pop();
        min_stack.pop();
      
    }
    
    public int top() {
        if(!data_stack.empty())
        {
           return data_stack.peek();
        }
        return 0;
    }
    
    public int min() {
        if(!min_stack.empty())
        {
            return min_stack.peek();
        }
        return 0;
    }
}