#include <cstdio>
#include <algorithm>
#include <set>
using namespace std;
const int INF = 2.e9;
const int NMAX = 100000;
struct lupu
{
    int x, y;
    lupu(int tx = 0, int ty = 0): x(tx), y(ty) {}
};
lupu v[NMAX + 5];
int cmp(lupu a, lupu b)
{
    if(a.y == b.y)
        return a.x > b.x;
    return a.y > b.y;
}
int main()
{
    freopen("lupu.in", "r", stdin);
    freopen("lupu.out", "w", stdout);
    int n, r, l, i, x, y, cnt, maxim;
    long long sum = 0;
    scanf("%d%d%d", &n, &r, &l);
    maxim = 0;
    for(i = 1 ; i <= n ; i ++)
    {
        scanf("%d%d", &x, &y);
        v[i]= {(r - x) / l + 1, y};
        maxim = max(maxim, (r - x) / l + 1);
    }
    sort(v + 1, v + n + 1, cmp);
    set <int> s;
    set <int>::iterator it;
    for(i = 1 ; i <= maxim ; i ++)
        s.insert(i);
    s.insert(INF);
    for(i = 1 ; i <= n ; i ++)
    {
        it = lower_bound(s.begin() , s.end() , v[i].x);
        if(it != s.begin() && (*it) != v[i].x)
          it --;
        if(*it <= v[i].x)
        {
            sum += v[i].y;
            s.erase(it);
        }
    }
    printf("%lld\n", sum);
    return 0;
}