Removing Stars From a String

class Solution {
public:
    string removeStars(string s) {
        stack<int> st;
        string s1="";
        for(int i=0;i<s.length();i++)
        {
            if(s[i]!='*')
            {
                st.push(s[i]);
            }
            else if(s[i]=='*' && !st.empty())
            {
                st.pop();
            }
        }
        while(!st.empty())
        {
           s1+=st.top();
           st.pop();
        }
        reverse(s1.begin(),s1.end());
       return s1;
    }
};