#include using namespace atcoder; using mint = modint998244353; const long long MOD = 998244353; // using mint = modint1000000007; // const long long MOD = 1000000007; // using mint = modint;//mint::set_mod(MOD); #include #define rep(i, a, b) for (ll i = (ll)(a); i < (ll)(b); i++) #define repeq(i, a, b) for (ll i = (ll)(a); i <= (ll)(b); i++) #define repreq(i, a, b) for (ll i = (ll)(a); i >= (ll)(b); i--) #define endl '\n' // fflush(stdout); #define cYes cout << "Yes" << endl #define cNo cout << "No" << endl #define sortr(v) sort(v, greater<>()) #define pb push_back #define pob pop_back #define mp make_pair #define mt make_tuple #define FI first #define SE second #define ALL(v) (v).begin(), (v).end() #define INFLL 3000000000000000100LL #define INF 1000000100 #define PI acos(-1.0L) #define TAU (PI * 2.0L) using namespace std; typedef long long ll; typedef pair Pll; typedef tuple Tlll; typedef vector Vi; typedef vector VVi; typedef vector Vl; typedef vector VVl; typedef vector VVVl; typedef vector VTlll; typedef vector Vm; typedef vector VVm; typedef vector Vs; typedef vector Vd; typedef vector Vc; typedef vector Vb; typedef vector VPll; typedef priority_queue PQl; typedef priority_queue, greater> PQlr; /* inout */ ostream &operator<<(ostream &os, mint const &m) { os << m.val(); return os; } template ostream &operator<<(ostream &os, const vector &v) { int n = v.size(); rep(i, 0, n) { os << v[i] << " \n"[i == n - 1]; } return os; } template ostream &operator<<(ostream &os, const vector> &v) { int n = v.size(); rep(i, 0, n) os << v[i]; return os; } template ostream &operator<<(ostream &os, pair const &p) { os << p.first << ' ' << p.second; return os; } template ostream &operator<<(ostream &os, const map &mp) { for (auto &[key, val] : mp) { os << key << ':' << val << '\n'; } return os; } template ostream &operator<<(ostream &os, const set &st) { auto itr = st.begin(); for (int i = 0; i < (int)st.size(); i++) { os << *itr << (i + 1 != (int)st.size() ? ' ' : '\n'); itr++; } return os; } template ostream &operator<<(ostream &os, multiset &st) { auto itr = st.begin(); for (int i = 0; i < (int)st.size(); i++) { os << *itr << (i + 1 != (int)st.size() ? ' ' : '\n'); itr++; } return os; } template ostream &operator<<(ostream &os, queue q) { while (q.size()) { os << q.front(); q.pop(); os << " \n"[q.empty()]; } return os; } template ostream &operator<<(ostream &os, stack st) { vector v; while (st.size()) { v.push_back(st.top()); st.pop(); } reverse(ALL(v)); os << v; return os; } template ostream &operator<<(ostream &os, priority_queue pq) { vector v; while (pq.size()) { v.push_back(pq.top()); pq.pop(); } os << v; return os; } template istream &operator>>(istream &is, vector &v) { for (T &in : v) is >> in; return is; } template istream &operator>>(istream &is, pair &p) { is >> p.first >> p.second; return is; } /* useful */ template int SMALLER(vector &a, T x) { return lower_bound(a.begin(), a.end(), x) - a.begin(); } template int orSMALLER(vector &a, T x) { return upper_bound(a.begin(), a.end(), x) - a.begin(); } template int BIGGER(vector &a, T x) { return a.size() - orSMALLER(a, x); } template int orBIGGER(vector &a, T x) { return a.size() - SMALLER(a, x); } template int COUNT(vector &a, T x) { return upper_bound(ALL(a), x) - lower_bound(ALL(a), x); } template bool chmax(T &a, S b) { if (a < b) { a = b; return 1; } return 0; } template bool chmin(T &a, S b) { if (a > b) { a = b; return 1; } return 0; } template void press(T &v) { v.erase(unique(ALL(v)), v.end()); } template vector zip(vector b) { pair p[b.size() + 10]; int a = b.size(); vector l(a); for (int i = 0; i < a; i++) p[i] = mp(b[i], i); sort(p, p + a); int w = 0; for (int i = 0; i < a; i++) { if (i && p[i].first != p[i - 1].first) w++; l[p[i].second] = w; } return l; } template vector vis(vector &v) { vector S(v.size() + 1); rep(i, 1, S.size()) S[i] += v[i - 1] + S[i - 1]; return S; } ll dem(ll a, ll b) { return ((a + b - 1) / (b)); } ll dtoll(double d, int g) { return round(d * pow(10, g)); } VVl gin(int n, int m = -1, bool zerodex = false, bool bi = true) { if (m == -1) m = n - 1; VVl gr(n); while (m--) { int a, b; cin >> a >> b; if (!zerodex) a--, b--; gr[a].pb(b); if (bi) gr[b].pb(a); } return gr; } unsigned long long randInt() { static unsigned int tx = 123456789, ty = 362436069, tz = 521288629, tw = 88675123; unsigned long long tt = (tx ^ (tx << 11)); tx = ty; ty = tz; tz = tw; return (tw = (tw ^ (tw >> 19)) ^ (tt ^ (tt >> 8))); } const double EPS = 1e-10; void init() { cin.tie(0); cout.tie(0); ios::sync_with_stdio(0); cout << fixed << setprecision(12); } // do {} while (next_permutation(ALL(vec))); /********************************** START **********************************/ void sol(); int main() { init(); int q = 1; cin >> q; while (q--) sol(); return 0; } /********************************** SOLVE **********************************/ void sol() { ll l, r, a, b; cin >> l >> r >> a >> b; ll ans1 = a * l + b; ll ans2 = a * r + b; cout << max(ans1, ans2) << endl; }