text: class Solution {
  public:
      int myAtoi(string str) {
          int ret = 0, fl = 1;
          for(auto i : str) {
              if(i < '0' || i > '9') continue;
              if(i == '-') fl = -1;
              else ret *= 10, ret += i - '0';
          }
          return ret * fl;
      }
  };