cc

#include <iostream>
using namespace std;

#define STACK_NUM 200
long stack_n[STACK_NUM];
static unsigned long stack_n_base = 0;
#define PUSH_DATA(n) do{stack_n[stack_n_base++] = n;} while(0)
#define POP_DATA(n) do{n = stack_n[--stack_n_base];} while(0)
#define EMPTY_STACK() (stack_n_base==0)

long Nth2(long x)
{
 long re = 0;
 long t;
 PUSH_DATA(x);
 while(!EMPTY_STACK())
 {
  POP_DATA(t);
  if(t < 1)
  {
   continue;
  }
  else
  {
   re += t;
   PUSH_DATA(t-1);
  }
 }
 return re;
}

int main()
{
 cout << Nth2(10);
 system("pause");
 return 0;
}