#include <bits/stdc++.h>   using namespace std;   int main() {     long long n, d, a, b;     cin >> n >> d >> a >> b;     vector<pair<long long, int> > v(n);     for (int i = 0; i < n; i++) {       long long x, y;       cin >> x >> y;       v[i].first = x * a + y * b;       v[i].second = i + 1;     }     sort(v.begin(), v.end());     int ans = 0, sum = 0, pos = 0;     for (int i = 0; i < n; i++) {       if (sum + v[i].first <= d) {         sum += v[i].first;         ans++;         pos = i;       }     }     cout << ans << endl;     if (ans)       for (int i = 0; i <= pos; i++) cout << v[i].second <<    ;     return 0;   }   