// Hazard
#include <bits/stdc++.h>
using namespace std;
#define int long long
constexpr int sizik = 1000 * 1001;
#define ar std::array
#define pr std::pair
#define vec std::vector
// #define GARY_DBG
#ifdef GARY_DBG
#ifndef GARY_LIB
#include <bits/stdc++.h>
#endif
// --- ANSI Color Codes ---
#define RESET "\033[0m"
#define RED "\033[31m" /* Red */
#define GREEN "\033[32m" /* Green */
#define YELLOW "\033[33m" /* Yellow */
#define BLUE "\033[34m" /* Blue */
#define MAGENTA "\033[35m" /* Magenta */
#define CYAN "\033[36m" /* Cyan */
// Overload for std::pair
template<typename T, typename U>
std::ostream& operator<<(std::ostream& os, const std::pair<T, U>& p) {
return os << '(' << p.first << ", " << p.second << ')';
}
// For std::tuple
template<typename... Ts>
std::ostream& operator<<(std::ostream& os, const std::tuple<Ts...>& t) {
os << '(';
std::apply(
[&os](const auto&... args) {
bool first = true;
((os << (first ? "" : ", ") << args, first = false), ...);
},
t);
return os << ')';
}
// For std::bitset
template<size_t N>
std::ostream& operator<<(std::ostream& os, const std::bitset<N>& b) {
return os << "bitset{" << b.to_string() << "}";
}
// Helper trait to detect if a type is a string
template<typename T>
struct is_string : std::false_type {};
template<>
struct is_string<std::string> : std::true_type {};
template<>
struct is_string<const char*> : std::true_type {};
template<>
struct is_string<char*> : std::true_type {};
// Overload for std::stack
// We pass by value to create a copy that we can pop from.
template<typename T, typename Container>
std::ostream& operator<<(std::ostream& os, std::stack<T, Container> s) {
os << "stack{top: ";
bool first = true;
while (!s.empty()) {
if (!first) os << ", ";
first = false;
os << s.top();
s.pop();
}
os << '}';
return os;
}
// Overload for std::queue
// We pass by value to create a copy that we can pop from.
template<typename T, typename Container>
std::ostream& operator<<(std::ostream& os, std::queue<T, Container> q) {
os << "queue{front: ";
bool first = true;
while (!q.empty()) {
if (!first) os << ", ";
first = false;
os << q.front();
q.pop();
}
os << '}';
return os;
}
// Overload for std::priority_queue
// We pass by value to create a copy that we can pop from.
template<typename T, typename Container, typename Compare>
std::ostream& operator<<(std::ostream& os, std::priority_queue<T, Container, Compare> pq) {
os << "pq{top: ";
bool first = true;
while (!pq.empty()) {
if (!first) os << ", ";
first = false;
os << pq.top();
pq.pop();
}
os << '}';
return os;
}
// Overload for containers (like vector, list, set, map, and deque) excluding strings
template<typename Container, typename std::enable_if<!is_string<Container>::value && !std::is_same<Container, std::string>::value &&
!std::is_same<Container, const char*>::value && !std::is_same<Container, char*>::value &&
!std::is_same<typename Container::value_type, char>::value,
int>::type = 0>
std::ostream& operator<<(std::ostream& os, const Container& container) {
os << '{';
bool first = true;
for (const auto& elem : container) {
if (!first) os << ", ";
first = false;
os << elem;
}
os << '}';
return os;
}
// Helper to print multiple arguments (tuple unpacking trick)
template<size_t Index = 0, typename... Ts>
typename std::enable_if<Index == sizeof...(Ts)>::type print_tuple(const std::tuple<Ts...>&) {
}
template<size_t Index = 0, typename... Ts>
typename std::enable_if < Index<sizeof...(Ts)>::type print_tuple(const std::tuple<Ts...>& t) {
if (Index > 0) std::cerr << ", ";
std::cerr << std::get<Index>(t);
print_tuple<Index + 1>(t);
}
// Debug macro
#define debug(...) \
do { \
std::cerr << MAGENTA << "[" << __FILE__ << ":" << __LINE__ << " (" << __func__ << ")]" << RESET << " -> "; \
std::cerr << "[" << #__VA_ARGS__ << "] ~> ["; \
print_tuple(std::make_tuple(__VA_ARGS__)); \
std::cerr << "]\n"; \
} while (0)
#else
#define debug(...) ((void)0)
#endif
typedef vec<vec<int>> _kra;
inline int readChar() {
static char buf[1 << 16];
static int idx = 0, n = 0;
if (idx >= n) {
n = fread(buf, 1, sizeof(buf), stdin);
idx = 0;
if (n == 0) return EOF;
}
return buf[idx++];
}
inline long long readInt() {
int c = readChar();
while (c <= ' ') {
if (c == EOF) return 0;
c = readChar();
}
bool neg = false;
if (c == '-') {
neg = true;
c = readChar();
}
long long x = 0;
while (c >= '0' && c <= '9') {
x = x * 10 + (c - '0');
c = readChar();
}
return neg ? -x : x;
}
inline int readDecimal() {
int c;
do {
c = readChar();
} while (c != '-' && (c < '0' || c > '9'));
bool neg = false;
if (c == '-') {
neg = true;
c = readChar();
}
long long val = 0;
while (c >= '0' && c <= '9') {
val = val * 10 + (c - '0');
c = readChar();
}
val *= 10000;
if (c == '.') {
int mul = 1000;
c = readChar();
while (mul >= 1 && c >= '0' && c <= '9') {
val += (c - '0') * mul;
mul /= 10;
c = readChar();
}
while (c >= '0' && c <= '9')
c = readChar();
}
return neg ? -val : val;
}
inline void printScaled(long long x) {
if (x < 0) {
putchar_unlocked('-');
x = -x;
}
long long intPart = x / 10000;
long long fracPart = x % 10000;
char buf[32];
int len = 0;
do {
buf[len++] = '0' + intPart % 10;
intPart /= 10;
} while (intPart > 0);
while (len--)
putchar_unlocked(buf[len]);
putchar_unlocked('.');
for (int p = 1000; p > 0; p /= 10) {
putchar_unlocked('0' + (fracPart / p) % 10);
}
}
void solve() {
int n = readInt();
int sum = 0, sum_a = 0, sum_b = 0;
std::vector<int> a(n), b(n);
std::vector<int> a_pref(n + 1), b_pref(n + 1);
for (int i = 0; i < n; i++) {
a[i] = readDecimal();
b[i] = readDecimal();
sum += a[i] + b[i];
sum_a += a[i];
sum_b += b[i];
}
std::sort(a.begin(), a.end(), std::greater<int>());
std::sort(b.begin(), b.end(), std::greater<int>());
for (int i = 1; i <= n; i++) {
a_pref[i] = a_pref[i - 1] + a[i - 1];
b_pref[i] = b_pref[i - 1] + b[i - 1];
}
int maxi = 0;
for (const auto& c : b_pref) {
maxi = std::max(maxi, c);
}
// debug(a, b, a_pref, b_pref);
debug(sum, sum_a, sum_b);
debug(a);
debug(b);
debug(a_pref);
debug(b_pref);
int wyn = 0;
for (int x = 1; x <= 2 * n; x++) {
debug(x, "NEW");
int L = std::max(0ll, x - n), R = std::min(x, n);
while (L < R) {
int s = (L + R + 1) / 2;
debug(L, R, s, a_pref[s], b_pref[x - s]);
if (a_pref[s] <= b_pref[x - s]) {
L = s;
} else {
R = s - 1;
}
}
int i = L;
int ans = std::min(a_pref[i], b_pref[x - i]);
debug(x, i);
debug(i, x - i);
if (i + 1 <= n && (x - (i + 1)) >= 0) {
ans = std::max(ans, std::min(a_pref[i + 1], b_pref[x - (i + 1)]));
}
if (i - 1 >= 0 && (x - (i - 1)) <= n) {
ans = std::max(ans, std::min(a_pref[i - 1], b_pref[x - (i - 1)]));
}
int local_wyn = ans - (x * 10000);
wyn = std::max(wyn, local_wyn);
}
printScaled(wyn);
putchar_unlocked('\n');
}
int32_t main() {
std::ios_base::sync_with_stdio(0);
std::cin.tie(0);
std::cout.tie(0);
int t = 1;
// std::cin >> t;
for (; t > 0; t--) {
solve();
}
return 0;
}
