URAL1068[Sum]

水题,不说。


CODE:


/*


PROGRAM: $PROGRAM


AUTHOR: Su Jiao


DATE: 2010-4-3


DESCRIPTION:


$DESCRIPTION


*/


#include <iostream>


using std::cin;


using std::cout;


#include <fstream>


using std::ifstream;


using std::ofstream;


#include <sstream>


using std::stringstream;


using std::endl;


#include <vector>


using std::vector;


#include <string>


using std::string;


#include <stack>


using std::stack;


#include <queue>


using std::queue;


#include <set>


using std::set;


#include <map>


using std::map;


using std::pair;


using std::make_pair;


#include <algorithm>


using std::sort;


#include <cassert>


//using std::assert;


 


class Application


{


      int N;


      static int abs(int a)


      {


             return a>0?a:-a;


      }


      public:


      Application()


      {


                   cin>>N;


      }


      int run()


      {


          cout<<(N+1)*(abs(N-1)+1)/2<<endl;


          return 0;


      }


};


 


int main()


{


    Application app;


    return app.run();


}