/** * author: otera * created: 03.08.2024 21:39:35 **/ // l_i - k < = p_i <= r_i - k // 値が小さい順にみると、区間スケジューリングみたいな感じか // つまり、各kに対して、O(n)で解ける // okなkは区間になるのでは? // 二分探索で上界、下界を求めたい? // r_iでsortしたくなる #include namespace otera {} using namespace std; using namespace otera; struct io_setup { io_setup(int precision = 20) { ios::sync_with_stdio(false); cin.tie(0); cout << fixed << setprecision(precision); } } io_setup_ {}; #define int long long using ll = long long; using ld = long double; using ull = unsigned long long; using i128 = __int128_t; using u128 = __uint128_t; #define repa(i, n) for(int i = 0; i < (n); ++ i) #define repb(i, a, b) for(int i = (a); i < (b); ++ i) #define repc(i, a, b, c) for(int i = (a); i < (b); i += (c)) #define overload4(a, b, c, d, e, ...) e #define overload3(a, b, c, d, ...) d #define rep(...) overload4(__VA_ARGS__, repc, repb, repa)(__VA_ARGS__) #define rep1a(i, n) for(int i = 1; i <= (n); ++ i) #define rep1b(i, a, b) for(int i = (a); i <= (b); ++ i) #define rep1c(i, a, b, c) for(int i = (a); i <= (b); i += (c)) #define rep1(...) overload4(__VA_ARGS__, rep1c, rep1b, rep1a)(__VA_ARGS__) #define rev_repa(i, n) for(int i=(n)-1;i>=0;i--) #define rev_repb(i, a, b) for(int i=(b)-1;i>=(a);i--) #define rev_rep(...) overload3(__VA_ARGS__, rev_repb, rev_repa)(__VA_ARGS__) #define rev_rep1a(i, n) for(int i=(n);i>=1;i--) #define rev_rep1b(i, a, b) for(int i=(b);i>=(a);i--) #define rev_rep1(...) overload3(__VA_ARGS__, rev_rep1b, rev_rep1a)(__VA_ARGS__) #define for_subset(t, s) for(ll t = (s); t >= 0; t = (t == 0 ? -1 : (t - 1) & (s))) typedef pair P; typedef pair LP; #define pb push_back #define pf push_front #define ppb pop_back #define ppf pop_front #define eb emplace_back #define mkp make_pair #define mkt make_tuple #define fr first #define sc second #define all(c) std::begin(c), std::end(c) #define rall(c) std::rbegin(c), std::rend(c) #define lb(c, x) distance(std::begin(c), lower_bound(all(c), (x))) #define ub(c, x) distance(std::begin(c), upper_bound(all(c), (x))) #define Sort(a) sort(all(a)) #define Rev(a) reverse(all(a)) #define Uniq(a) sort(all(a));(a).erase(unique(all(a)),std::end(a)) #define si(c) (int)(c).size() inline ll popcnt(ull a){ return __builtin_popcountll(a); } #define kth_bit(x, k) ((x>>k)&1) #define unless(A) if(!(A)) #define elif else if ll modulo(ll n, ll d){ return (n % d + d) % d; }; ll intpow(ll a, ll b){ ll ans = 1; while(b){ if(b & 1) ans *= a; a *= a; b /= 2; } return ans; } ll intpow(ll a, ll b, ll m) {ll ans = 1; while(b){ if(b & 1) (ans *= a) %= m; (a *= a) %= m; b /= 2; } return ans; } template inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; } template inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; } template constexpr inline int pow_m1(T n) { return -(n & 1) | 1; } template constexpr inline T fld(const T x, const T y) { return (x ^ y) >= 0 ? x / y : (x - (y + pow_m1(y >= 0))) / y; } template constexpr inline T cld(const T x, const T y) { return (x ^ y) <= 0 ? x / y : (x + (y + pow_m1(y >= 0))) / y; } #define INT(...) int __VA_ARGS__;in(__VA_ARGS__) #define LL(...) ll __VA_ARGS__;in(__VA_ARGS__) #define ULL(...) ull __VA_ARGS__;in(__VA_ARGS__) #define STR(...) string __VA_ARGS__;in(__VA_ARGS__) #define CHR(...) char __VA_ARGS__;in(__VA_ARGS__) #define DBL(...) double __VA_ARGS__;in(__VA_ARGS__) #define LD(...) ld __VA_ARGS__;in(__VA_ARGS__) #define vec(type,name,...) vectorname(__VA_ARGS__) #define VEC(type,name,size) vectorname(size);in(name) #define vv(type,name,h,...) vector>name(h,vector(__VA_ARGS__)) #define VV(type,name,h,w) vector>name(h,vector(w));in(name) #define vvv(type,name,h,w,...) vector>>name(h,vector>(w,vector(__VA_ARGS__))) template using vc = vector; template using vvc = vector>; template using vvvc = vector>; template using vvvvc = vector>; template using pq = priority_queue; template using pqg = priority_queue, greater>; template using umap = unordered_map; template void scan(T& a){ cin >> a; } template void scan(vector& a){ for(auto&& i : a) scan(i); } void in(){} template void in(Head& head, Tail&... tail){ scan(head); in(tail...); } void print(){ cout << ' '; } template void print(const T& a){ cout << a; } template void print(const vector& a){ if(a.empty()) return; print(a[0]); for(auto i = a.begin(); ++i != a.end(); ){ cout << ' '; print(*i); } } int out(){ cout << '\n'; return 0; } template int out(const T& t){ print(t); cout << '\n'; return 0; } template int out(const Head& head, const Tail&... tail){ print(head); cout << ' '; out(tail...); return 0; } #define CHOOSE(a) CHOOSE2 a #define CHOOSE2(a0,a1,a2,a3,a4,x,...) x #define debug_1(x1) cout<<#x1<<": "< l(n), r(n); rep(i, n) { in(l[i], r[i]); -- l[i]; } // [l[i], r[i]) auto check = [&](int k) -> int { pqg

pque; vvc g(n); rep(i, n) { if(l[i] - k < 0) { pque.emplace(r[i] - k, i); } else if(l[i] - k < n) { g[l[i] - k].eb(i); } } rep(i, n) { for(int id: g[i]) { pque.emplace(r[id] - k, id); } if(pque.empty()) return 1; auto [val, id] = pque.top(); pque.pop(); unless(i < val) { return -1; } } return 0; }; int le = -inf, ri = inf; bool flag = 0; int ok = -1; assert(check(le) == 1); assert(check(ri) == -1); while(ri - le > 1) { int mid = (le + ri) / 2; int val = check(mid); if(val == 0) { flag = 1; ok = mid; break; } else if(val == 1) { le = mid; } else { ri = mid; } } if(check(le) == 0) { flag = 1; ok = le; } if(check(ri) == 0) { flag = 1; ok = ri; } if(!flag) { out(0); return; } int mi = -1, ma = -1; { le = -inf, ri = ok; while(ri - le > 1) { int mid = (le + ri) / 2; if(check(mid) == 0) ri = mid; else le = mid; } mi = ri; } { le = ok, ri = inf; while(ri - le > 1) { int mid = (le + ri) / 2; if(check(mid) == 0) le = mid; else ri = mid; } ma = le; } int ans = ma - mi + 1; out(ans); } signed main() { int testcase = 1; // in(testcase); while(testcase--) solve(); return 0; }