#line 1 "a.cpp" #line 2 "/home/nok0/documents/programming/library/template/header.hpp" #include #line 3 "/home/nok0/documents/programming/library/template/def_const.hpp" const int inf = 1000000000; const long long INF = 1000000000000000000ll; #line 4 "/home/nok0/documents/programming/library/template/debug.hpp" namespace viewer { void view(const long long &e) { if(e == INF) std::cerr << "INF"; else if(e == -INF) std::cerr << "-INF"; else std::cerr << e; } void view(const int &e) { if(e == inf) std::cerr << "inf"; else if(e == -inf) std::cerr << "-inf"; else std::cerr << e; } template void view(const T &e) { std::cerr << e; } template void view(const std::pair &p) { std::cerr << "("; view(p.first); std::cerr << ", "; view(p.second); std::cerr << ")"; } template void view(const std::tuple &p) { std::cerr << "("; view(std::get<0>(p)); std::cerr << ", "; view(std::get<1>(p)); std::cerr << ", "; view(std::get<2>(p)); std::cerr << ")"; } template void view(const std::tuple &p) { std::cerr << "("; view(std::get<0>(p)); std::cerr << ", "; view(std::get<1>(p)); std::cerr << ", "; view(std::get<2>(p)); std::cerr << ", "; view(std::get<3>(p)); std::cerr << ")"; } template void view(const std::set &s) { if(s.empty()) { std::cerr << "{ }"; return; } std::cerr << "{ "; for(auto &t : s) { view(t); std::cerr << ", "; } std::cerr << "\b\b }"; } template void view(const std::unordered_set &s) { if(s.empty()) { std::cerr << "{ }"; return; } std::cerr << "{ "; for(auto &t : s) { view(t); std::cerr << ", "; } std::cerr << "\b\b }"; } template void view(const std::multiset &s) { if(s.empty()) { std::cerr << "{ }"; return; } std::cerr << "{ "; for(auto &t : s) { view(t); std::cerr << ", "; } std::cerr << "\b\b }"; } template void view(const std::unordered_multiset &s) { if(s.empty()) { std::cerr << "{ }"; return; } std::cerr << "{ "; for(auto &t : s) { view(t); std::cerr << ", "; } std::cerr << "\b\b }"; } template void view(const std::vector &v) { if(v.empty()) { std::cerr << "{ }"; return; } std::cerr << "{ "; for(const auto &e : v) { view(e); std::cerr << ", "; } std::cerr << "\b\b }"; } template void view(const std::array &v) { if(v.empty()) { std::cerr << "{ }"; return; } std::cerr << "{ "; for(const auto &e : v) { view(e); std::cerr << ", "; } std::cerr << "\b\b }"; } template void view(const std::vector> &vv) { std::cerr << "{\n"; for(const auto &v : vv) { std::cerr << "\t"; view(v); std::cerr << '\n'; } std::cerr << "}"; } template void view(const std::vector> &v) { std::cerr << "{\n"; for(const auto &c : v) { std::cerr << "\t("; view(c.first); std::cerr << ", "; view(c.second); std::cerr << ")\n"; } std::cerr << "}"; } template void view(const std::vector> &v) { if(v.empty()) { std::cerr << "{ }"; return; } std::cerr << '{'; for(const auto &t : v) { std::cerr << "\n\t"; view(t); std::cerr << ","; } std::cerr << "\n}"; } template void view(const std::vector> &v) { if(v.empty()) { std::cerr << "{ }"; return; } std::cerr << '{'; for(const auto &t : v) { std::cerr << "\n\t"; view(t); std::cerr << ","; } std::cerr << "\n}"; } template void view(const std::map &m) { std::cerr << "{\n"; for(const auto &t : m) { std::cerr << "\t["; view(t.first); std::cerr << "] : "; view(t.second); std::cerr << '\n'; } std::cerr << "}"; } template void view(const std::unordered_map &m) { std::cerr << "{\n"; for(const auto &t : m) { std::cerr << "\t["; view(t.first); std::cerr << "] : "; view(t.second); std::cerr << '\n'; } std::cerr << "}"; } } // namespace viewer // when compiling : g++ foo.cpp -DLOCAL #ifdef LOCAL void debug_out() {} template void debug_out(Head H, Tail... T) { viewer::view(H); std::cerr << ", "; debug_out(T...); } #define debug(...) \ do { \ std::cerr << __LINE__ << " [" << #__VA_ARGS__ << "] : ["; \ debug_out(__VA_ARGS__); \ std::cerr << "\b\b]\n"; \ } while(0) #define dump(x) \ do { \ std::cerr << __LINE__ << " " << #x << " : "; \ viewer::view(x); \ std::cerr << '\n'; \ } while(0) #else #define debug(...) (void(0)) #define dump(x) (void(0)) #endif #line 3 "/home/nok0/documents/programming/library/template/def_name.hpp" #define pb push_back #define eb emplace_back #define fi first #define se second #define SZ(x) ((int)(x).size()) #define all(x) (x).begin(), (x).end() #define rall(x) (x).rbegin(), (x).rend() #define popcnt(x) __builtin_popcountll(x) template using V = std::vector; template using VV = std::vector>; template using pqup = std::priority_queue, std::greater>; using ll = long long; using ld = long double; using int128 = __int128_t; using pii = std::pair; using pll = std::pair; #line 3 "/home/nok0/documents/programming/library/template/fast_io.hpp" struct fast_io { fast_io() { std::ios::sync_with_stdio(false); std::cin.tie(nullptr); std::cout << std::fixed << std::setprecision(15); } } fast_io_; #line 3 "/home/nok0/documents/programming/library/template/input.hpp" template std::istream &operator>>(std::istream &is, std::pair &p) { is >> p.first >> p.second; return is; } template std::istream &operator>>(std::istream &is, std::vector &v) { for(T &i : v) is >> i; return is; } std::istream &operator>>(std::istream &is, __int128_t &a) { std::string s; is >> s; __int128_t ret = 0; for(int i = 0; i < (int)s.length(); i++) if('0' <= s[i] and s[i] <= '9') ret = 10 * ret + s[i] - '0'; a = ret * (s[0] == '-' ? -1 : 1); return is; } namespace scanner { void scan(int &a) { std::cin >> a; } void scan(long long &a) { std::cin >> a; } void scan(std::string &a) { std::cin >> a; } void scan(char &a) { std::cin >> a; } void scan(char a[]) { std::ignore = std::scanf("%s", a); } void scan(double &a) { std::cin >> a; } void scan(long double &a) { std::cin >> a; } template void scan(std::pair &p) { std::cin >> p; } template void scan(std::vector &a) { std::cin >> a; } void INPUT() {} template void INPUT(Head &head, Tail &...tail) { scan(head); INPUT(tail...); } } // namespace scanner #define VEC(type, name, size) \ std::vector name(size); \ scanner::INPUT(name) #define VVEC(type, name, h, w) \ std::vector> name(h, std::vector(w)); \ scanner::INPUT(name) #define INT(...) \ int __VA_ARGS__; \ scanner::INPUT(__VA_ARGS__) #define LL(...) \ long long __VA_ARGS__; \ scanner::INPUT(__VA_ARGS__) #define STR(...) \ std::string __VA_ARGS__; \ scanner::INPUT(__VA_ARGS__) #define CHAR(...) \ char __VA_ARGS__; \ scanner::INPUT(__VA_ARGS__) #define DOUBLE(...) \ double __VA_ARGS__; \ scanner::INPUT(__VA_ARGS__) #define LD(...) \ long double __VA_ARGS__; \ scanner::INPUT(__VA_ARGS__) #line 3 "/home/nok0/documents/programming/library/template/math.hpp" template inline bool chmin(T &a, const U &b) { return a > b ? a = b, true : false; } template inline bool chmax(T &a, const U &b) { return a < b ? a = b, true : false; } template T divup(T x, T y) { return (x + y - 1) / y; } template T POW(T a, long long n) { T ret = 1; while(n) { if(n & 1) ret *= a; a *= a; n >>= 1; } return ret; } long long POW(long long a, long long n, const int mod) { long long ret = 1; a = (a % mod + mod) % mod; while(n) { if(n & 1) (ret *= a) %= mod; (a *= a) %= mod; n >>= 1; } return ret; } template T bin_search(T ok, T ng, const F &f) { while(abs(ok - ng) > 1) { T mid = (ok + ng) >> 1; (f(mid) ? ok : ng) = mid; } return ok; } template T bin_search(T ok, T ng, const F &f, int loop) { for(int i = 0; i < loop; i++) { T mid = (ok + ng) / 2; (f(mid) ? ok : ng) = mid; } return ok; } #line 3 "/home/nok0/documents/programming/library/template/output.hpp" template std::ostream &operator<<(std::ostream &os, const std::pair &p) { os << p.first << " " << p.second; return os; } template std::ostream &operator<<(std::ostream &os, const std::vector &a) { for(int i = 0; i < int(a.size()); ++i) { if(i) os << " "; os << a[i]; } return os; } std::ostream &operator<<(std::ostream &dest, __int128_t &value) { std::ostream::sentry s(dest); if(s) { __uint128_t tmp = value < 0 ? -value : value; char buffer[128]; char *d = std::end(buffer); do { --d; *d = "0123456789"[tmp % 10]; tmp /= 10; } while(tmp != 0); if(value < 0) { --d; *d = '-'; } int len = std::end(buffer) - d; if(dest.rdbuf()->sputn(d, len) != len) { dest.setstate(std::ios_base::badbit); } } return dest; } template void print(const T a) { std::cout << a << '\n'; } template void print(Head H, Tail... T) { std::cout << H << ' '; print(T...); } template void println(const T a) { std::cout << a << '\n'; } template void println(const std::vector &a) { for(const auto &v : a) std::cout << v << '\n'; } template void println(Head H, Tail... T) { std::cout << H << '\n'; println(T...); } void Yes(const bool b = true) { std::cout << (b ? "Yes\n" : "No\n"); } void No() { std::cout << "No\n"; } void YES(const bool b = true) { std::cout << (b ? "YES\n" : "NO\n"); } void NO() { std::cout << "NO\n"; } #line 2 "/home/nok0/documents/programming/library/template/rep.hpp" #define foa(v, a) for(auto &v : a) #define repname(a, b, c, d, e, ...) e #define rep(...) repname(__VA_ARGS__, rep3, rep2, rep1, rep0)(__VA_ARGS__) #define rep0(x) for(int rep_counter = 0; rep_counter < (x); ++rep_counter) #define rep1(i, x) for(int i = 0; i < (x); ++i) #define rep2(i, l, r) for(int i = (l); i < (r); ++i) #define rep3(i, l, r, c) for(int i = (l); i < (r); i += (c)) #define repsname(a, b, c, ...) c #define reps(...) repsname(__VA_ARGS__, reps1, reps0)(__VA_ARGS__) #define reps0(x) for(int reps_counter = 1; reps_counter <= (x); ++reps_counter) #define reps1(i, x) for(int i = 1; i <= (x); ++i) #define rrepname(a, b, c, ...) c #define rrep(...) rrepname(__VA_ARGS__, rrep1, rrep0)(__VA_ARGS__) #define rrep0(x) for(int rrep_counter = (x)-1; rrep_counter >= 0; --rrep_counter) #define rrep1(i, x) for(int i = (x)-1; i >= 0; --i) #line 3 "/home/nok0/documents/programming/library/template/string_converter.hpp" struct string_converter { char start = 0; char type(const char &c) const { return (islower(c) ? 'a' : isupper(c) ? 'A' : isdigit(c) ? '0' : 0); } int convert(const char &c) { if(!start) start = type(c); return c - start; } int convert(const char &c, const std::string &chars) { return chars.find(c); } template auto convert(const T &v) { std::vector ret; ret.reserve(size(v)); for(auto &&e : v) ret.emplace_back(convert(e)); return ret; } template auto convert(const T &v, const std::string &chars) { std::vector ret; ret.reserve(size(v)); for(auto &&e : v) ret.emplace_back(convert(e, chars)); return ret; } int operator()(const char &v, char s = 0) { start = s; return convert(v); } int operator()(const char &v, const std::string &chars) { return convert(v, chars); } template auto operator()(const T &v, char s = 0) { start = s; return convert(v); } template auto operator()(const T &v, const std::string &chars) { return convert(v, chars); } } toint; #line 3 "/home/nok0/documents/programming/library/template/vector.hpp" template int lb(const std::vector &a, const T x) { return std::distance((a).begin(), std::lower_bound((a).begin(), (a).end(), (x))); } template int ub(const std::vector &a, const T x) { return std::distance((a).begin(), std::upper_bound((a).begin(), (a).end(), (x))); } template void UNIQUE(std::vector &a) { std::sort(a.begin(), a.end()); a.erase(std::unique(a.begin(), a.end()), a.end()); } template std::vector press(std::vector &a) { auto res = a; UNIQUE(res); for(auto &v : a) v = lb(res, v); return res; } #define SORTname(a, b, c, ...) c #define SORT(...) SORTname(__VA_ARGS__, SORT1, SORT0, ...)(__VA_ARGS__) #define SORT0(a) std::sort((a).begin(), (a).end()) #define SORT1(a, c) std::sort((a).begin(), (a).end(), [](const auto x, const auto y) { return x c y; }) template void ADD(std::vector &a, const T x = 1) { for(auto &v : a) v += x; } template void SUB(std::vector &a, const T x = 1) { for(auto &v : a) v -= x; } template struct cum_vector { public: cum_vector() = default; template cum_vector(const std::vector &vec) : cum((int)vec.size() + 1) { for(int i = 0; i < (int)vec.size(); i++) cum[i + 1] = cum[i] + vec[i]; } T prod(int l, int r) { return cum[r] - cum[l]; } private: std::vector cum; }; std::vector> rle(const std::string &s) { const int n = s.size(); std::vector> ret; ret.reserve(n); for(int l = 0; l < n;) { int r = l + 1; for(; r < n and s[l] == s[r]; r++) {} ret.emplace_back(s[l], r - l); l = r; } return ret; } template std::vector> rle(const std::vector &v) { const int n = v.size(); std::vector> ret; ret.reserve(n); for(int l = 0; l < n;) { int r = l + 1; for(; r < n and v[l] == v[r]; r++) {} ret.emplace_back(v[l], r - l); l = r; } return ret; } std::vector iota(int n) { std::vector p(n); std::iota(p.begin(), p.end(), 0); return p; } #line 12 "/home/nok0/documents/programming/library/template/all" using namespace std; #line 2 "a.cpp" struct bitvector { ll n = 0; vector a; vector cm; bitvector() {} bitvector(ll n_) : n(n_), a(n), cm(n + 1) {} bool operator[](ll i) const { return a[i]; } void set(ll i, bool x) { a[i] = x; } void build() { for(ll i = 0; i < n; ++i) cm[i + 1] = cm[i] + a[i]; } ll rank(bool x, ll k) { // k個目(1-origin)までのxの個数 return x ? cm[k] : k - cm[k]; } ll num(bool x, ll l, ll r) { //[l,r]のxの個数 ll nm1 = cm[r + 1] - cm[l]; return x ? nm1 : r - l + 1 - nm1; } // friend ostream &operator << (ostream &os,const bitvector &a){ // for (ll i=0;i a; //元配列 vector bs; // bs[lv]:第lvビット列 lv=h-1(上)~0(下) vector mid; // mid[lv]:第lvビット列の0の個数(=第lv-1ビット列の01境界位置) ll mxv = -INF; //最大値 waveletmatrix() {} waveletmatrix(const vector &a_) : n((ll)a_.size()), a(a_) { if(a.empty()) return; //最大値、bit数を得る ll mx = mxv = *max_element(a.begin(), a.end()); while(mx > 1) mx >>= 1, ++h; //構築 bs.resize(h, bitvector(n)); mid.resize(h); vector s = a; for(ll lv = h - 1; lv >= 0; --lv) { bitvector &b = bs[lv]; //ビット列作成 for(ll i = 0; i < n; ++i) { b.set(i, (s[i] >> lv) & 1); } b.build(); // 01境界位置記録 mid[lv] = b.rank(0, n); //第lv-1ビット用に配列入れ替え vector tmp(n); ll l = 0, r = b.rank(0, n); for(ll i = 0; i < n; ++i) { if(b[i]) tmp[r++] = s[i]; else tmp[l++] = s[i]; } s.swap(tmp); } } ll nthsmall(ll l, ll r, ll k) { //[l,r]内昇順k番目の値 1-origin ない時-1 if(r < l || n <= l || r < 0 || k < 1) return -1; chmax(l, 0LL), chmin(r, n - 1); if(r - l + 1 < k) return -1; ++r; ll ret = 0; for(ll lv = h - 1; lv >= 0; --lv) { bitvector &b = bs[lv]; ll lznm = b.rank(0, l); ll rznm = b.rank(0, r); ll lonm = l - lznm; ll ronm = r - rznm; ll znm = rznm - lznm; if(k <= znm) { //左 l = lznm, r = rznm; } else { //右 ret |= 1ll << lv; l = mid[lv] + lonm; r = mid[lv] + ronm; k -= znm; } } return ret; } ll leftnumof(ll l, ll r, ll x) { //[l,r]内x以下の個数 auto [p, q] = rangefreq(l, r, x); return p + q; } ll rightnumof(ll l, ll r, ll x) { //[l,r]内x以上の個数 return r - l + 1 - rangefreq(l, r, x).first; } ll numof(ll l, ll r, ll x) { //[l,r]内xの個数 return rangefreq(l, r, x).second; } ll numof(ll l, ll r, ll x, ll y) { //[l,r]内x以上y以下の個数 return leftnumof(l, r, y) - rangefreq(l, r, x).first; // n(y以下)-n(x未満) } ll nthbig(ll l, ll r, ll k) { //[l,r]内降順k番目の値 1-origin ない時-1 if(r < l || n <= l || r < 0 || k < 1) return -1; chmax(l, 0LL), chmin(r, n - 1); return nthsmall(l, r, r - l + 2 - k); } ll floorval(ll l, ll r, ll x) { //[l,r]内x以下最大の値 ない時-1 ll k = leftnumof(l, r, x); return nthsmall(l, r, k); } ll ceilval(ll l, ll r, ll x) { //[l,r]内x以上最小の値 ない時INF auto [k, _] = rangefreq(l, r, x); ll ret = nthsmall(l, r, k + 1); return ret == -1 ? INF : ret; } //---- utility ll down(ll lv, ll i, bool x) { return bs[lv].rank(x, i) + mid[lv] * x; } //!< ↑第lvビット列の境界i(i-1とiの間)のlv-1での位置 //!< ↑ 戻り値をretとすると位置ret-1とretの間が境界 ll down(ll lv, ll i) { return down(lv, i, bs[lv][i]); } //!< ↑第lvビット列の位置iのlv-1での位置 pll succ(ll l, ll r, bool x, ll lv) { return {down(lv, l, x), down(lv, r, x)}; } //!< ↑第lvビット列の[l,r)のlv-1での範囲 pll rangefreq(ll l, ll r, ll x) { //[l,r]内のx未満/x の個数 if(r < l || n <= l || r < 0 || x < 0) return {0, 0}; chmax(l, 0LL), chmin(r, n - 1); if(x > mxv) return {r - l + 1, 0}; ++r; ll ret = 0; for(ll lv = h - 1; lv >= 0; --lv) { ll len = r - l; bool xb = (x >> lv) & 1; tie(l, r) = succ(l, r, xb, lv); if(xb) ret += len - (r - l); } return {ret, r - l}; } }; /* . ↓vector 0以上 waveletmatrix wm(a); ll nm=wm.leftnumof(l,r,x); //[l,r]内x以下の個数 ll nm=wm.rightnumof(l,r,x);//[l,r]内x以上の個数 ll nm=wm.numof(l,r,x); //[l,r]内xの個数 ll nm=wm.numof(l,r,x,y); //[l,r]内x以上y以下の個数 ll v=wm.nthsmall(l,r,k); //[l,r]内小さい方からk番目の値 1-origin ない時-1 ll v=wm.nthbig(l,r,k); //[l,r]内大きい方からk番目の値 1-origin ない時-1 ll v=wm.floorval(l,r,x); //[l,r]内x以下最大の値 ない時-1 ll v=wm.ceilval(l,r,x); //[l,r]内x以上最小の値 ない時INF */ template struct waveletmatrix2d { using Int = long long; using ll = long long; using TS = pair; waveletmatrix wm; vector xys; //全点昇順 uniqしない vector ys; S none; /*---- コンストラクタ ----*/ waveletmatrix2d() {} waveletmatrix2d(const vector &xys_, S none_ = -INF) : xys(xys_), none(none_) { for(auto &&[x, y] : xys) ys.push_back(y); init(); } waveletmatrix2d(const vector &xs, const vector &ys_, S none_ = -INF) : ys(ys_), none(none_) { ll n = xs.size(); assert(ys.size() == n); for(ll i = 0; i < n; ++i) xys.emplace_back(xs[i], ys[i]); init(); } /*---- I/F ----*/ Int size() const { return (Int)xys.size(); } // Int numof(T sx,T ex,S sy,S ey){ //矩形[sx,ex,sy,ey]内の個数 境界含む //} // S nthsmall(T sx,T ex,Int k){ //[sx,ex]内、y座標小さい方からk番目 1-origin ない時none //} // S nthbig(T sx,T ex,Int k){ //[sx,ex]内、y座標大きい方からk番目 1-origin ない時none //} // S biggest(T sx,T ex,S ey){ //[sx,ex]内、ey以下で最大のy ない時none //} S smallest(T sx, T ex, S sy) { //[sx,ex]内、sy以上で最小のy ない時NONE auto [l, r] = xrange2lr(sx, ex); ll sj = ceilIdxY(sy); ll j = wm.ceilval(l, r, sj); return j == INF ? none : ys[j]; } /*---- utility ----*/ void init() { sort(xys.begin(), xys.end()); sort(ys.begin(), ys.end()); ys.erase(unique(ys.begin(), ys.end()), ys.end()); vector ini; for(auto &&[x, y] : xys) { ll j = lower_bound(ys.begin(), ys.end(), y) - ys.begin(); ini.push_back(j); } wm = waveletmatrix(ini); } static bool cmpx(const TS &a, const TS &b) { return a.first < b.first; } ll floorIdxX(T x) { // x以下最大に対応するi ない時-1 return upper_bound(xys.begin(), xys.end(), TS{x, S()}, cmpx) - xys.begin() - 1; } ll ceilIdxX(T x) { // x以上最小に対応するi ない時size() return lower_bound(xys.begin(), xys.end(), TS{x, S()}, cmpx) - xys.begin(); } ll floorIdxY(S y) { // y以下最大に対応するj ない時-1 return upper_bound(ys.begin(), ys.end(), y) - ys.begin() - 1; } ll ceilIdxY(S y) { // y以上最小に対応するj ない時ys.size() return lower_bound(ys.begin(), ys.end(), y) - ys.begin(); } pair xrange2lr(T sx, T ex) { return {ceilIdxX(sx), floorIdxX(ex)}; } }; using wm2d = waveletmatrix2d; /* - -------- 定義 -------- wm2d wm(xy); . ↓無効値(smallest等の戻り値用) waveletmatrix2d wm(xy,-1e300); - -------- アクセス -------- ll y=wm.smallest(sx,ex,sy); //[sx,ex]内、sy以上で最小のy ない時wm.none if (y==wm.none) … //ない時の判定法 */ void main_(); int main() { int t = 1; while(t--) main_(); } void main_() { LL(n, b, c, x); ll day = b + c; VEC(ll, a, n - 1); V cum(n); rep(i, n - 1) cum[i + 1] = cum[i] + a[i]; vector> dp(n); dp[0][0] = 0; auto is_safe = [&](ll ti) { return ti % day <= b; }; auto nxt_good = [&](ll ti) { if(is_safe(ti)) return ti; else return ti + day - ti % day; }; auto mchmin = [&](int idx, ll j, ll val) { if(dp[idx].count(j)) chmin(dp[idx][j], val); else dp[idx][j] = val; }; V bis(n); rep(i, n) bis[i] = {cum[i] % day, i}; wm2d wm(bis, INF); auto calc_k = [&](int i, ll t) -> ll { ll l = (b + 1 - t + cum[i]) % day; if(l < 0) l += day; ll r = (day - 1 - t + cum[i]) % day; if(r < 0) r += day; ll k = INF; if(l <= r) { chmin(k, wm.smallest(l, r, i + 1)); } else { chmin(k, wm.smallest(0, r, i + 1)); chmin(k, wm.smallest(l, day - 1, i + 1)); } return k; }; ll ans = INF; rep(i, n - 1) { for(auto [j, now] : dp[i]) { ll k = calc_k(i, j); if(k > n - 1 or cum.back() - (x - now) <= cum[k]) { chmin(ans, nxt_good(max(now, now + cum.back() - cum[i] - (x - now)))); continue; } ll nxt_time = j + cum[k] - cum[i]; mchmin(k, nxt_good(nxt_time), now); ll bef = nxt_time; if(bef % day > b) bef -= bef % day - b; assert(is_safe(bef) and bef <= nxt_time); ll nxt_used = now + nxt_time - bef; if(nxt_used <= x) { mchmin(k, bef, nxt_used); } } } print(ans); }