#include <library.h>

// Three different functions, all pretty basic

// A - add up all the numbers in a particular range
// first method: find the sum of the rest of the range, and just add the first to it.

int addupa(const int start, const int end)
{ 
   // special case, only one number

   if (start == end)
     return start;

   // what is 1+2+3+4+5+6+7 ?
   // what is 2+3+4+5+6+7? add one to that

   // general pattern
   const int rest = addupa(start + 1, end);
   return start + rest; }



// B - add up all the numbers in a particular range
// second method: split the range in half. Find the sums of the two halves, and add them

int addupb(const int start, const int end)
{ 
   // special case, only one number

   if (start == end)
     return start;

   // what is 1+2+3+4+5+6+7 ?
   // what is 1+2+3+4
   // what is 5+6+7
   // add them for the answer

   // general pattern
   const int middle = (start + end) / 2;
   const int first_half = addupb(start, middle);
   const int second_half = addupb(middle + 1, end);
   return first_half + second_half; }



// C - find the sum of all the values of 3*i*i over a given range
// pretty much the same as A really.

int addupc(const int start, const int end)
{ 
  // sum of 3 i squared for a going from start to end

   if (start == end)
     return 3*start*start;

   const int rest = addupc(start + 1, end);
   return 3*start*start + rest; }



void main()
{ const int a = read_int();
  const int b = read_int();
  print(addupc(a, b));
  new_line(); }