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