#include <stdio.h>
#include <vector>
#include <iterator>
using namespace std;

#define f "lupu.in"
#define out "lupu.out"

vector< vector<int> > a;
vector<int> timp;
vector<int> val;
vector<bool> sel;
int n, d, t;

int main()
{
    int tmax=0, x;
    freopen(f,"r",stdin);
    freopen(out,"w",stdout);

    scanf("%d%d%d",&n,&t,&d);

    val.resize(n+1);
    a.resize(2);
    timp.resize(n+1);
    sel.resize(n+1);

    for ( int i = 1; i <= n; i++ )
    {
        scanf("%d%d",&x,&val[i]);

        if ( x > t ) timp[i] = -1;
        else         timp[i] = (t-x)/d;

        if ( tmax < (t-x)/d ) tmax = (t-x)/d;
    }

    for ( int i = 0; i <= 1; i++ ) a[i].resize(tmax+1);

    int poz, maxim;

    for ( int i = 1; i <= n; i++ )
        if ( a[0][tmax] < val[i] && timp[i] >= tmax ) a[0][tmax] = val[i], poz = i;

    sel[poz] = 1;

    for ( int j = tmax-1; j >= 0; j-- )
    {
        maxim = 0;
        for ( int i = 1; i <= n; i++ )
        {
            if ( sel[i] || timp[i] < j || timp[i] == -1 ) continue;

            if ( a[1][j] < a[0][j+1] + val[i] )
            {
                 a[1][j] = a[0][j+1] + val[i];
                 if ( maxim < a[1][j] ) maxim = a[1][j], poz = i;
            }
        }
        a[0][j] = maxim;
        sel[poz] = 1;
    }

  /*  for ( int j = 0; j <= tmax; j++ )
     {
         for ( int i = 0; i <= 1; i++ )
         {
             printf("%d ", a[i][j] );
         }
         printf("\n");

     }*/

    //for ( int i = 1; i <= n; i++ ) printf("%d ", );

    printf("%d",a[0][0]);
}