#include<cstdio>
#include<queue>
#include<algorithm>
using namespace std;
struct oaie
{
    int a,d;
};
priority_queue<int>q;
bool cmp(oaie a,oaie b)
{
    return a.d>b.d;
}
oaie o[100005];
int n,i,j,k,l,x,m,maxi;
long long ans;
int main()
{
    freopen("lupu.in","r",stdin);
    freopen("lupu.out","w",stdout);
    scanf("%d%d%d",&n,&x,&l);
    for(i=1;i<=n;i++)
    {
        scanf("%d%d",&j,&k);
        if(j<=x)
        {
            o[++m].d=(x-j)/l;
            o[m].a=k;
            maxi=max(maxi,o[m].d);
        }
    }
    sort(o+1,o+m+1,cmp);
    j=1;
    for(i=maxi;i>=0;i--)
    {
        while(o[j].d==i) q.push(o[j++].a);
        if(q.size())
        {
            ans+=q.top();
            q.pop();
        }
    }
    printf("%lld\n",ans);
    return 0;
}