#include<cstdio>
#include<algorithm>
using std::sort;

struct oaie
{
	int v,d;
	bool operator<(const oaie o)const
		{
			return v>o.v;
		}
} v[100005];

int main()
{
	freopen ("lupu.in","r",stdin);
	freopen ("lupu.out","w",stdout);
	
	int n,x,l;
	scanf ("%d%d%d", &n, &x, &l);

	for(int i=0;i<n;i++)
		scanf ("%d%d", &v[i].d, &v[i].v);

	sort (v,v+n);

	int r=0;
	for(int i=0;i<n;i++)
		if(v[i].d<=x){
			x-=l;
			r+=v[i].v;
		}

	printf ("%d",r);
	return 0;
}