text: #include <iostream>
  #include <vector>
  #include <string>
  #include <stack>
  #include <queue>
  #include <map>
  #include <set>
  #include <unordered_set>
  #include <unordered_map>
  using namespace std;
  
  /*
  use two stacks
  */
  class Solution {
  public:
      int calculate(string s) {
          
      }
  };
  
  int main(){
  
  
  
  
      return 0;
  }