#include<cstdio> 
#include<algorithm>
using namespace std;
long n; 
long long j,x,l,nr=0,s=0,y,z; 
struct oaie 
{   
long long dist,lana; 
}; 
oaie a[100005]; 
long long h[100005];
inline bool cmp(oaie v,oaie w)
{
	return v.dist<w.dist;
}
void down(int m) 
{ 
int fiu,aux;     
do    
{         
fiu=0;         
if(m+m<=nr)         
{    
fiu=m+m;             
if(m+m+1<=nr&&h[m+m+1]>h[fiu])            
fiu=m+m+1; 
} 
if(fiu)             
if(h[fiu]>h[m])        
{    
aux=h[m];                 
h[m]=h[fiu];          
h[fiu]=aux;   
}    
else                
fiu=0;    
}while(fiu); 
} 
void build() 
{     
int m;     
for(m=nr/2;m>=1;m--)     
down(m); 
}
int main() 
{     
freopen("lupu.in","r",stdin);     
freopen("lupu.out","w",stdout); 
long i;    
scanf("%ld%ld%ld",&n,&x,&l); 
for(i=1;i<=n;i++) 
scanf("%lld%lld",&a[i].dist,&a[i].lana); 
sort(a+1,a+1+n,cmp);
y=1; 
z=x%l;   
for(j=0;j<=x/l;j++)     
{ 
for(i=y;i<=n;i++)         
	if(a[i].dist<=z) 
		h[++nr]=a[i].lana;
	else
		
		break;
build(); 
s+=h[1]; 
h[1]=0; 
y=i; 
z=z+l; 
} 
printf("%lld\n",s);     
return 0; 
}