#include<stdio.h>
#include<vector>
#include<queue>
using namespace std;
vector<long long> v[100005];
struct Str
{
    long long c,d;
} a[100005];
priority_queue<long long> q;
int main()
{
    freopen("lupu.in","r",stdin);
    freopen("lupu.out","w",stdout);
    long long n,i,x,l;
    scanf("%lld%lld%lld",&n,&x,&l);
    for(i=1;i<=n;i++)
    {
        scanf("%lld%lld",&a[i].d,&a[i].c);
        ///a[i].t = ziua maxima in care poate fi luata i:
        if(a[i].d<=x)
            v[((x-a[i].d)/l+1)>n?n:((x-a[i].d)/l+1)].push_back(i);
    }
    long long ans=0;
    for(long long t=n;t>=1;t--)
    {
        for(long long i=0;i<(long long)v[t].size();i++)
            q.push(a[v[t][i]].c);
        if(!q.empty())
            ans+=q.top(),
            q.pop();
    }
    printf("%lld\n",ans);
    return 0;
}