#include <stdio.h>
#include <stdlib.h>
int sort1(const void *x, const void *y) {      //functie de comparare pt sortare
      return (*(int*)y - *(int*)x);            //sortare descrescatoare
}
void sorta2(unsigned long int a[][2],unsigned long int n){     // apelare qsort pt a 
	qsort(a,n,sizeof(unsigned long int[2]),sort1);
}

void add (unsigned long int a[],unsigned long int gr,unsigned long int in,unsigned long int &sf){ //functie de adaugare  in vector ordonat crescator
	if(sf==in)  {   			//inserare initiala						
		a[t]=gr;
		sf++;
		return;
	}
	if(gr<=a[in]) {				//la inceput 
		for(int i=sf;i>in;i--) 
 			a[i]=a[i-1];
		a[in]=gr;
		sf++;
		return;
 	}
	if(gr>=a[sf-1]) {			//la sfarsit
		a[sf]=gr;
		sf++;
		return;
 	}
	for(int i=in;i<sf;i++)			  //inserare intre 
		if(a[i]<=gr&&gr<=a[i+1]) {
			for(int j=sf;j>i+1;j--) 
 				a[j]=a[j-1];
			a[i+1]=gr;
			sf++;
			return;
			}
}
void print(unsigned long int a[],unsigned long int t, unsigned long int n){
	for(int i=t;i<n;i++)
		printf(" %ld ",a[i]);
	printf("\n");
}
unsigned long int gutui(unsigned long int c[][2],unsigned long int n,unsigned long int h,unsigned long int u){
	unsigned long int i,k=0,m=0,z;
	unsigned long int *a;
	unsigned long int sf=0,in=0;
	a=(unsigned long int *)malloc(n*sizeof(unsigned long int));
	if(u>=h) {
		for(i=0;i<n;i++)
			if(m<c[i][1]&&c[i][0]<=h)
				m=c[i][1];
		return m; }
	for(i=0;i<n;i++) 
		if(c[i][0]>h)  {c[i][0]=0;c[i][1]=0;}					
	sorta2(c,n); 
	for(i=0;i<n;i++)
		
		if(k<=h-c[i][0])  { 
				m=m+c[i][1];
				add(a,c[i][1],in,sf);
				k=k+u;
				}
			else  if(c[i][1]>a[in])
									
				         { 
					   m=m-a[in];
				          in++; 	           
					  m=m+c[i][1];
					   add(a,c[i][1],in,sf);			
					}    				
				
			return m;
}
int main(){
	 unsigned long int c[100000][2];
	 unsigned long int i,n,h,gr,j,u,a1,a2;
         freopen("gutui.in", "r", stdin);
         freopen("gutui.out", "w", stdout); 
         scanf("%ld",&n);
	 scanf("%ld",&h);
	 scanf("%ld",&u);
 	 for (i=0;i<n;i++) { 
     	 		scanf("%ld",&c[i][0]); 
			scanf("%ld",&c[i][1]);
	}
	gr=gutui(c,n,h,u);
	printf("%ld\n",gr);
	return 0;
}