#include<stdio.h>

#define MAX_N 100000+1
long long int n,nn,x,l,k;
long long int sol;
long long int A[MAX_N],Heap[MAX_N];
long long int T_MAX = -1;
long long int T[MAX_N];

void read(),solve(),heapUp(long long int),heapDown(long long int),heapDown2(long long int);
int main()
{
	freopen("lupu.in","r",stdin);
	freopen("lupu.out","w",stdout);

	read();
	solve();
	printf("%lld\n",sol);

	fclose(stdin); fclose(stdout);
	return 0;
}


void qsort(int st,int dr)
{
    int pivot=T[(st+dr)/2];
    int i=st;
    int j=dr;
    while(i<=j)
    {
        while(pivot>T[i]&&i<=n) i++;
        while(pivot<T[j]&&j>0) j--;
        if(i<=j)
        {
            if(i!=j){
                T[i]^=T[j]^=T[i]^=T[j];
                A[i]^=A[j]^=A[i]^=A[j];
            }
            i++;
            j--;
        }
    }
    if(st<j) qsort(st,j);
    if(i<dr) qsort(i,dr);

}

void read()
{
	long long int i;
	scanf("%lld%lld%lld",&n,&x,&l);
	T_MAX = x/l+1;
	for(i = 1; i <= n; i++)
	{
		scanf("%lld %lld",&T[i],&A[i]);
		if(T[i] <= x)
		{
		     T[i] = (x-T[i])/l+1;
		}
        else
        {
	         n--; i--;
        }
	}
	qsort(1,n);
}


void solve()
{
	long long int i;
    long long int pos = n;
	for(i = T_MAX; i >= 1; i--)
	{
		while(T[pos] == i)
		{
			Heap[++k] = A[pos];
			heapUp(k);
			pos--;
		}
		if(k)
		{
			sol+= Heap[1];
			Heap[1] = Heap[k];
			Heap[k--]=0;
			heapDown(1);
		}
	}
}

void heapUp(long long int v)
{
	long long int key = Heap[v];
	while(v > 1 && key > Heap[v/2])
	{
	    int t=Heap[v/2];
		Heap[v/2] = Heap[v];
		Heap[v]=t;
		v/=2;
	}
	Heap[v] = key;
}

void heapDown(long long int v)
{
	long long int w = v*2;
	while(w <= k)
	{
		if(w+1 <= k && Heap[w+1] > Heap[w]) w++;
		if(Heap[v] >= Heap[w]) return;

		Heap[w] ^= Heap[v] ^= Heap[w] ^= Heap[v];
		v = w;
		w *= 2;
	}
}