/**
 * Sample solution for Roller Coaster
 *   Steven J Zeil, 10/23/2010
 */
#include <algorithm>
#include <cmath>
#include <fstream>
#include <iostream>
#include <iterator>

using namespace std;



/**
 * Process a single dataset for the problem.
 * Return true if successful. Return false if we encounter the
 * end of input marker or an unreocverable I/O error,
 */
bool processDataSet (istream& in)
{
  int N, K;
  long L;
  in >> N >> K >> L;
  if (N == 0)
    return false;

  long dizzyLimit = L + 1L;

  int fun[1000];
  int dizzy[1000];
  for (int i = 0; i < N; ++i)
    in >> fun[i] >> dizzy[i];

  // Dynamic programming setup: f[i] is minimum dizziness possible 
  //   while achieving fun=i
  long* oldf = new long[20*N+1];
  long * newf = new long[20*N+1];
  fill_n (oldf, 20*N+1, dizzyLimit);
  oldf[0] = 0;
  
  int maxFunSoFar = 0;
  for (int track = 0; track < N; ++track)
    {
      fill_n (newf, 20*N+1, dizzyLimit);
      for (int i = 0; i <= maxFunSoFar; ++i)
	{
	  if (oldf[i] < dizzyLimit)
	    {
	      // If Bessie keeps her eyes open
	      int newFun = i + fun[track];
	      long newDizzy = min (oldf[i] + (long)(dizzy[track]), dizzyLimit);
	      newf[newFun] = min(newf[newFun], newDizzy);
	      
	      // If Bessie closes her eyes
	      newFun = i;
	      newDizzy = max(oldf[i] - (long)K, 0L);
	      newf[newFun] = min(newf[newFun], newDizzy);
	    }
	}

      //copy (newf, newf+20*N+1, ostream_iterator<long>(cout, " "));
      //cout << endl;

      maxFunSoFar = maxFunSoFar + fun[track];
      swap (oldf, newf);
    }

  for (int i = 20*N; i >= 0; --i)
    if (oldf[i] < dizzyLimit)
      {
	cout << i << endl;
	break;
      }
  delete [] oldf;
  delete [] newf;
  return true;
}



void rollerCoaster (istream& in)
{
	bool finished = false;
	while (!finished)
	{
		finished = !processDataSet(in);
	}
}

int main (int argc, char** argv)
{
	// Program should normally read from standard in. But
	// for debugging purposes, it is sometimes easier to
	// give a file name on the command line.
	if (argc > 1)
	{
		ifstream in (argv[1]);
		rollerCoaster (in);
	}
	else
		rollerCoaster(cin);

	return 0;
}