text: #include<iostream>
  #include<fstream>
  #include<vector>
  
  
  using namespace std;
  
  struct longNumber
  {
    vector<int> _num;
    longNumber(long long a = 0)
    {
      while(a!=0)
      {
        _num.push_back(a%10);
        a/=10;
      }
    }
    int size()
    {
      return _num.size();
    }
  
    void setSize(int n)
    {
      _num.assign(n,0);
    }
  
    void _normalize()
    {
      while(_num[_num.size()-1]==0)
        _num.pop_back();
    }
  
    void print()
    {
      if(size()==0)
        cout << 0;
      else
        for(int i = size()-1; i>=0; i--)
          cout << _num[i];
  
    }
  
    int & operator [](int a)
    {
      return _num[a];
    }
  
    longNumber operator +(longNumber a)
    {
      longNumber tmp(0);
      int cameFromBack = 0;
      tmp.setSize(max(this->size(), a.size())+1);
      for(int i = 0; i<tmp.size(); i++)
      {
        tmp[i] = cameFromBack;
        if(a.size()>i)
          tmp[i]+=a[i];
        if(this->size()>i)
          tmp[i]+=a[i];
        cameFromBack = tmp[i]/10;
        tmp[i]%=10;
      }
      tmp._normalize();
      return tmp;
    }
  
  };
  
  int main()
  {
    int n;
    int k;
    cin >> n;
    longNumber a(n);
    a.print();
    return 0;
  }
  