LeetCode 2 :Min Stack

#include <iostream>
#include <stack>
using std::stack;

class MinStack {
public:
    stack<int> st;
    stack<int> stm;
    void push(int x) 
    {
        st.push(x);
        if(stm.empty() || stm.top()>=x)
        {
            stm.push(x);
        }
    }

    void pop() 
    {
        int topElem = st.top();
        st.pop();
        if(topElem <= stm.top())
        {
            stm.pop();
        }

    }

    int top() 
    {
        return st.top();
    }

    int getMin() 
    {
        return stm.top();
    }
};