#include<cstdio>
#include<vector>
#include<algorithm>
using namespace std;
vector<pair<int,int> > V;
int n,m,l,x,y,SOL[100010],solcnt,L,cnt,i;
long long SOLUTIE;
int main()
{
    freopen("lupu.in","r",stdin);
    freopen("lupu.out","w",stdout);
    scanf("%d%d%d",&n,&m,&l);
    for(i=1;i<=n;i++)
    {
        scanf("%d%d",&x,&y);
        V.push_back(make_pair(x,y));
    }
    sort(V.rbegin(),V.rend());
    L=0;cnt=1;
    for(vector<pair<int,int> >::iterator it=V.begin();it!=V.end();it++)
    {
        x=(*it).first;
        y=(*it).second;
        if(x+L>m)continue;
        if(x+L<=m&&x+L+l>m)
        {
            SOL[++solcnt]=-y;
            continue;
        }
        sort(SOL+1,SOL+solcnt+1);
        solcnt=cnt;
        ++cnt;
        --it;
        L+=l;
    }
    for(i=1;i<=cnt;i++)
        SOLUTIE+=(long long)(-SOL[i]);
    printf("%lld\n",SOLUTIE);
    return 0;
}