/* #region Head */ #include using namespace std; using ll = long long; using ull = unsigned long long; using ld = long double; using pll = pair; template using vc = vector; template using vvc = vc>; using vll = vc; using vvll = vvc; using vld = vc; using vvld = vvc; using vs = vc; using vvs = vvc; template using um = unordered_map; template using pq = priority_queue; template using pqa = priority_queue, greater>; template using us = unordered_set; #define REP(i, m, n) for (ll i = (m), i##_len = (ll)(n); i < i##_len; ++(i)) #define REPM(i, m, n) for (ll i = (m), i##_max = (ll)(n); i <= i##_max; ++(i)) #define REPR(i, m, n) for (ll i = (m), i##_min = (ll)(n); i >= i##_min; --(i)) #define REPD(i, m, n, d) for (ll i = (m), i##_len = (ll)(n); i < i##_len; i += (d)) #define REPMD(i, m, n, d) for (ll i = (m), i##_max = (ll)(n); i <= i##_max; i += (d)) #define REPI(itr, ds) for (auto itr = ds.begin(); itr != ds.end(); itr++) #define ALL(x) begin(x), end(x) #define SIZE(x) ((ll)(x).size()) #define PERM(c) \ sort(ALL(c)); \ for (bool c##p = 1; c##p; c##p = next_permutation(ALL(c))) #define UNIQ(v) v.erase(unique(ALL(v)), v.end()); #define endl '\n' #define sqrt sqrtl #define floor floorl #define log2 log2l constexpr ll INF = 1'010'000'000'000'000'017LL; constexpr ll MOD = 1'000'000'007LL; // 1e9 + 7 constexpr ld EPS = 1e-12; constexpr ld PI = 3.14159265358979323846; template istream &operator>>(istream &is, vc &vec) { // vector 入力 for (T &x : vec) is >> x; return is; } template ostream &operator<<(ostream &os, vc &vec) { // vector 出力 (for dump) os << "{"; REP(i, 0, SIZE(vec)) os << vec[i] << (i == i_len - 1 ? "" : ", "); os << "}"; return os; } template ostream &operator>>(ostream &os, vc &vec) { // vector 出力 (inline) REP(i, 0, SIZE(vec)) os << vec[i] << (i == i_len - 1 ? "\n" : " "); return os; } template istream &operator>>(istream &is, pair &pair_var) { // pair 入力 is >> pair_var.first >> pair_var.second; return is; } template ostream &operator<<(ostream &os, pair &pair_var) { // pair 出力 os << "(" << pair_var.first << ", " << pair_var.second << ")"; return os; } // map, um, set, us 出力 template ostream &out_iter(ostream &os, T &map_var) { os << "{"; REPI(itr, map_var) { os << *itr; auto itrcp = itr; if (++itrcp != map_var.end()) os << ", "; } return os << "}"; } template ostream &operator<<(ostream &os, map &map_var) { return out_iter(os, map_var); } template ostream &operator<<(ostream &os, um &map_var) { return out_iter(os, map_var); } template ostream &operator<<(ostream &os, set &set_var) { return out_iter(os, set_var); } template ostream &operator<<(ostream &os, us &set_var) { return out_iter(os, set_var); } template ostream &operator<<(ostream &os, pq &pq_var) { pq pq_cp(pq_var); os << "{"; if (!pq_cp.empty()) { os << pq_cp.top(), pq_cp.pop(); while (!pq_cp.empty()) os << ", " << pq_cp.top(), pq_cp.pop(); } return os << "}"; } // dump #define DUMPOUT cerr void dump_func() { DUMPOUT << endl; } template void dump_func(Head &&head, Tail &&... tail) { DUMPOUT << head; if (sizeof...(Tail) > 0) DUMPOUT << ", "; dump_func(move(tail)...); } // chmax (更新「される」かもしれない値が前) template > bool chmax(T &xmax, const U &x, Comp comp = {}) { if (comp(xmax, x)) { xmax = x; return true; } return false; } // chmin (更新「される」かもしれない値が前) template > bool chmin(T &xmin, const U &x, Comp comp = {}) { if (comp(x, xmin)) { xmin = x; return true; } return false; } // ローカル用 #define DEBUG_ #ifdef DEBUG_ #define DEB #define dump(...) \ DUMPOUT << " " << string(#__VA_ARGS__) << ": " \ << "[" << to_string(__LINE__) << ":" << __FUNCTION__ << "]" << endl \ << " ", \ dump_func(__VA_ARGS__) #else #define DEB if (false) #define dump(...) #endif struct AtCoderInitialize { static constexpr int IOS_PREC = 15; static constexpr bool AUTOFLUSH = false; AtCoderInitialize() { ios_base::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr); cout << fixed << setprecision(IOS_PREC); if (AUTOFLUSH) cout << unitbuf; } } ATCODER_INITIALIZE; string yes = "Yes", no = "No"; // string yes = "YES", no = "NO"; void yn(bool p) { cout << (p ? yes : no) << endl; } /* #endregion */ /* #region Rational */ class RationalNum { friend RationalNum operator+(const RationalNum &left, const RationalNum &right); friend RationalNum operator-(const RationalNum &left, const RationalNum &right); friend RationalNum operator*(const RationalNum &left, const RationalNum &right); friend RationalNum operator/(const RationalNum &left, const RationalNum &right); friend bool operator==(const RationalNum &left, const RationalNum &right); friend bool operator!=(const RationalNum &left, const RationalNum &right); friend bool operator<(const RationalNum &left, const RationalNum &right); friend bool operator>(const RationalNum &left, const RationalNum &right); friend bool operator<=(const RationalNum &left, const RationalNum &right); friend bool operator>=(const RationalNum &left, const RationalNum &right); friend ostream &operator<<(ostream &out, const RationalNum &obj); friend istream &operator>>(istream &in, RationalNum &obj); public: RationalNum(); RationalNum(double x); RationalNum(int numerator_, int denominator_ = 1); RationalNum &operator=(const RationalNum &obj); RationalNum &operator+=(const RationalNum &obj); RationalNum &operator-=(const RationalNum &obj); RationalNum &operator*=(const RationalNum &obj); RationalNum &operator/=(const RationalNum &obj); RationalNum &operator++(); RationalNum operator++(int); RationalNum &operator--(); RationalNum operator--(int); RationalNum operator+() const; RationalNum operator-() const; void setNumerator(int numerator_); int getNumerator() const; void setDenominator(int denominator_); int getDenominator() const; private: int numerator; int denominator; void simplify(); }; void getFactors(int num, vector &factorSet) { if (num != 1) factorSet.push_back(num); for (int i = 2; i * i <= num; ++i) { if (num % i == 0) factorSet.push_back(i), factorSet.push_back(num / i); } } void simplifyFun(int &a, int &b) { int tempN = a, tempD = b; int small, temp; vector factorSet; if (tempN == tempD) { a = 1, b = 1; return; } else if (tempN == -tempD) { a = -1, b = 1; return; } else if (tempN == 0) { b = 1; return; } small = min(abs(tempN), abs(tempD)); getFactors(small, factorSet); for (int i = 0; i < factorSet.size(); i++) { temp = factorSet[i]; while (tempN % temp == 0 && tempD % temp == 0) tempN /= temp, tempD /= temp; } if (b < 0) tempN *= -1, tempD *= -1; a = tempN, b = tempD; } /* #region RationalFriendFunctions */ RationalNum operator+(const RationalNum &left, const RationalNum &right) { RationalNum temp; int tempLD = left.getDenominator(); int tempRD = right.getDenominator(); simplifyFun(tempLD, tempRD); temp.setDenominator(left.getDenominator() * tempRD); temp.setNumerator(left.getNumerator() * tempRD + right.getNumerator() * tempLD); temp.simplify(); return temp; } RationalNum operator-(const RationalNum &left, const RationalNum &right) { return left + (-right); } RationalNum operator*(const RationalNum &left, const RationalNum &right) { RationalNum temp; RationalNum temp_2(right.getNumerator(), left.getDenominator()); RationalNum temp_3(left.getNumerator(), right.getDenominator()); int a = temp_2.getDenominator(); int b = temp_2.getNumerator(); int c = temp_3.getDenominator(); int d = temp_3.getNumerator(); temp.setNumerator(b * d); temp.setDenominator(a * c); return temp; } RationalNum operator/(const RationalNum &left, const RationalNum &right) { RationalNum temp_1(left.getNumerator(), left.getDenominator()); RationalNum temp_2(right.getDenominator(), right.getNumerator()); return temp_1 * temp_2; } bool operator==(const RationalNum &left, const RationalNum &right) { return (left.numerator == right.numerator && left.denominator == right.denominator); } bool operator!=(const RationalNum &left, const RationalNum &right) { return !(left == right); } bool operator<(const RationalNum &left, const RationalNum &right) { int lside = left.getNumerator() * right.getDenominator(); int rside = left.getDenominator() * right.getNumerator(); return (lside < rside); } bool operator>(const RationalNum &left, const RationalNum &right) { int lside = left.getNumerator() * right.getDenominator(); int rside = left.getDenominator() * right.getNumerator(); return (lside > rside); } bool operator<=(const RationalNum &left, const RationalNum &right) { return ((left < right) || (left == right)); } bool operator>=(const RationalNum &left, const RationalNum &right) { return ((left > right) || (left == right)); } // 出力 ostream &operator<<(ostream &out, const RationalNum &obj) { out << obj.numerator; if (obj.numerator != 0 && obj.denominator != 1) out << "/" << obj.denominator; return out; } // 入力 istream &operator>>(istream &in, RationalNum &obj) { string inputstr; int num = 0; int sign = 1; bool slashExist = false; bool dotExist = false; bool validInput = true; int virtualDenominator = 1; cin >> inputstr; for (int i = 0; i < inputstr.size(); i++) { char temp = inputstr[i]; if (temp == '.') { if (dotExist == false && slashExist == false && i != 0) { dotExist = true; } else { validInput = false; break; } } else if (temp == '/') { if (dotExist == false && slashExist == false && i != 0) { slashExist = true; obj.setNumerator(sign * num); num = 0; sign = 1; } else { validInput = false; break; } } else if (temp == '-') { if (i == 0) { sign = -sign; } else if (inputstr[i - 1] == '/') { sign = -sign; } else { validInput = false; break; } } else if (temp <= '9' && temp >= '0') { if (dotExist) { if (virtualDenominator > INT_MAX / 10) { cout << "this frational is too long to handle."; validInput = false; break; } else { virtualDenominator *= 10; } } if (num > INT_MAX / 10) { cout << "this number is too long to handle."; validInput = false; break; } num *= 10; num += inputstr[i] - '0'; } else { validInput = false; break; } } if (validInput == false) { obj.setNumerator(0); obj.setDenominator(1); cout << "Input is not valid! The whole set to 0" << endl; } else { if (slashExist == true) { obj.setDenominator(sign * num); } else if (dotExist) { obj.setNumerator(sign * num); obj.setDenominator(virtualDenominator); } else { obj.setNumerator(sign * num); obj.setDenominator(1); } } obj.simplify(); return in; } /* #endregion */ /* #region RationalMemberFunctions */ RationalNum::RationalNum() { setNumerator(0), setDenominator(1); } RationalNum::RationalNum(double x) { int i = 1; while (x * i - static_cast(x * i) != 0) { if (i > INT_MAX / 10) { cout << "this frational number : " << x << " can not be transfer to rational number, it's too long, now set it 0." << endl; setNumerator(0); setDenominator(1); return; } else { i *= 10; } } setNumerator(x * i); setDenominator(i); simplify(); } RationalNum::RationalNum(int numerator_, int denominator_) { setNumerator(numerator_); setDenominator(denominator_); simplify(); } RationalNum &RationalNum::operator=(const RationalNum &obj) { setNumerator(obj.getNumerator()), setDenominator(obj.getDenominator()); return *this; } RationalNum &RationalNum::operator+=(const RationalNum &obj) { return *this = *this + obj; } RationalNum &RationalNum::operator-=(const RationalNum &obj) { return *this = *this - obj; } RationalNum &RationalNum::operator*=(const RationalNum &obj) { return *this = *this * obj; } RationalNum &RationalNum::operator/=(const RationalNum &obj) { return *this = *this / obj; } RationalNum &RationalNum::operator++() { return *this = *this + 1; } RationalNum RationalNum::operator++(int) { RationalNum before = *this; *this = *this + 1; return before; } RationalNum &RationalNum::operator--() { return *this = *this - 1; } RationalNum RationalNum::operator--(int) { RationalNum before = *this; *this = *this - 1; return before; } RationalNum RationalNum::operator+() const { return *this; } RationalNum RationalNum::operator-() const { RationalNum temp; temp.setNumerator(-getNumerator()); temp.setDenominator(getDenominator()); return temp; } void RationalNum::setNumerator(int numerator_) { numerator = numerator_; } int RationalNum::getNumerator() const { return numerator; } void RationalNum::setDenominator(int denominator_) { if (denominator_ == 0) { denominator = 1, numerator = 0; cerr << "Denominator is 0! Not good! THe whole is set to 0." << endl; } else { denominator = denominator_; } } int RationalNum::getDenominator() const { return denominator; } void RationalNum::simplify() { int tempN = numerator, tempD = denominator; simplifyFun(tempN, tempD); setNumerator(tempN); setDenominator(tempD); } /* #endregion */ /* #endregion */ // Problem void solve() { int n; cin >> n; vc x(n), y(n); REP(i, 0, n) cin >> x[i] >> y[i]; vc vertical(101, 0); map, int> lines; REP(i, 0, n - 1) REP(j, i + 1, n) { if (x[i] == x[j]) { ++vertical[x[i]]; } else { RationalNum a = y[j] - y[i]; a /= x[j] - x[i]; RationalNum b = -a * x[i] + y[i]; pair key = make_pair(a, b); lines[key]; ++lines[key]; // if ((i == 0 || i == 1) && (j == 1 || j == 3)) dump(i, j, a, b); } } um linenum2pointnum; linenum2pointnum[0] = 0; REPM(i, 2, 10000) linenum2pointnum[i * (i - 1) / 2] = i; int ma = linenum2pointnum[*max_element(ALL(vertical))]; // dump(vertical, ma); REPI(itr, lines) chmax(ma, linenum2pointnum[itr->second]); //, (dump(itr->first.first, itr->first.second, itr->second)); cout << ma << endl; // dump(lines); } // entry point int main() { solve(); return 0; }