#include <cstdio>
#include <algorithm>
#include <queue>
#include <cctype>
using namespace std;
const int INF = INT_MAX;
const int NMAX = 100000;
char buffer[1 << 17];
int sz = (1 << 17), crs = (1 << 17);
void get_int(int &n)
{
    for( ; crs < sz && !isdigit(buffer[crs]) ; crs ++);
    if(crs == sz)
    {
        fread(buffer, sz, 1, stdin);
        for(crs = 0 ; crs < sz && !isdigit(buffer[crs]) ; crs ++);
    }
    n = 0;
    for( ; crs < sz && isdigit(buffer[crs]) ; crs ++)
        n = n * 10 + buffer[crs] - '0';
    if(crs == sz)
    {
        fread(buffer, sz, 1, stdin);
        for(crs = 0 ; crs < sz && isdigit(buffer[crs]) ; crs ++)
            n = n * 10 + buffer[crs] - '0';
    }
}
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)
{
    return a.x > b.x;
}
int main()
{
    freopen("lupu.in", "r", stdin);
    freopen("lupu.out", "w", stdout);
    int n, r, l, i, j, x, y, cnt, maxim;
    long long s = 0;
    get_int(n);
    get_int(r);
    get_int(l);
    maxim = 0;
    for(i = 1 ; i <= n ; ++ i)
    {
        get_int(x);
        get_int(y);
        v[i] = {(r - x) / l + 1, y};
        maxim = max(maxim, (r - x) / l + 1);
    }
    sort(v + 1, v + n + 1, cmp);
    priority_queue <int> pq;
    j = 1;
    for(i = maxim ; i >= 1 ; i --)
    {
        for( ; j <= n && v[j].x == i ; j ++)
            pq.push(v[j].y);
        if(!pq.empty())
        {
            s += pq.top();
            pq.pop();
        }
    }
    printf("%lld\n", s);
    return 0;
}