#include <bits/stdc++.h>
using namespace std;pair<int,int> v[100005];priority_queue<int> q;int main(){int n,x,l,d,a,k=1,t,i,pas;long long s=0;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", &d, &a);if (d<=x)v[k++]={(x-d)/l+1,a};}sort(v+1,v+k+1);t=v[k].first;for (pas=t;pas>=1;pas--) {while (k>=1 && v[k].first==pas) {q.push(v[k].second);k--;}if (!q.empty()) {s+=q.top();q.pop();}}printf("%lld", s);}