func_code_string: #include <bits/stdc++.h>   using namespace std;   template <typename T>   vector<T>& operator--(vector<T>& v) {     for (auto& i : v) --i;     return v;   }   template <typename T>   vector<T>& operator++(vector<T>& v) {     for (auto& i : v) ++i;     return v;   }   template <typename T>   istream& operator>>(istream& is, vector<T>& v) {     for (auto& i : v) is >> i;     return is;   }   template <typename T>   ostream& operator<<(ostream& os, vector<T>& v) {     for (auto& i : v) os << i <<    ;     return os;   }   template <typename T, typename U>   istream& operator>>(istream& is, pair<T, U>& p) {     is >> p.first >> p.second;     return is;   }   template <typename T, typename U>   ostream& operator<<(ostream& os, pair<T, U>& p) {     os << p.first <<     << p.second;     return os;   }   template <typename T, typename U>   pair<T, U> operator-(pair<T, U> a, pair<T, U> b) {     return make_pair(a.first - b.first, a.second - b.second);   }   template <typename T, typename U>   pair<T, U> operator+(pair<T, U> a, pair<T, U> b) {     return make_pair(a.first + b.first, a.second + b.second);   }   template <typename T, typename U>   void umin(T& a, U b) {     if (a > b) a = b;   }   template <typename T, typename U>   void umax(T& a, U b) {     if (a < b) a = b;   }   int main() {     int T;     cin >> T;     while (T--) {       long long a, b, p, q;       cin >> a >> b >> p >> q;       long long t = min(b - a + 1, (long long)sqrt(b - a) + 5);       vector<pair<long long, int>> v;       auto g = [&](long long x) { return p * x * 2 % (q * 2); };       auto f = [&](long long x) { return abs(g(x) - q); };       42;       ;       for (int i = 0; i < t; ++i) {         v.emplace_back(g(i), i);       }       long long ans = a;       sort(v.begin(), v.end());       42;       ;       for (long long i = a; i + t <= b + 1; i += t) {         long long need = (q - g(i) + q * 2) % (q * 2);         int ind = (lower_bound((v).begin(), (v).end(), (make_pair(need, -1))) -                    (v).begin());         for (int j = ind - 3; j <= ind + 3; ++j) {           int k = (j + v.size()) % v.size();           long long fn = f(i + v[k].second);           if (fn < f(ans) || (fn == f(ans) && i + v[k].second < ans))             ans = i + v[k].second;         }         ind = (upper_bound((v).begin(), (v).end(), (make_pair(need, -1))) -                (v).begin());         for (int j = ind - 3; j <= ind + 3; ++j) {           int k = (j + v.size()) % v.size();           long long fn = f(i + v[k].second);           if (fn < f(ans) || (fn == f(ans) && i + v[k].second < ans))             ans = i + v[k].second;         }       }       for (long long i = b; i >= max(b - t - 5, a); --i) {         long long fn = f(i);         if (fn < f(ans) || (fn == f(ans) && i < ans)) ans = i;       }       cout << ans <<   n ;     }     return 0;   }   