#include <bits/stdc++.h>
#define in(x) freopen(x, "r", stdin)
#define out(x) freopen(x, "w", stdout)
using namespace std;
const int man = (int)(2e5 + 500);
int n, ans;
int nt[man], sz[man];
vector <int> g[man];
set <pair <int, int> > s[man];
void upd(int f1, int f2, int f3) {
// cerr << f1 << " " << f2 << " " << f3 << "\n";
if (ans == -1) {
ans = max(max(f1, f2), f3) - min(min(f1, f2), f3);
}
ans = min(ans, max(max(f1, f2), f3) - min(min(f1, f2), f3));
}
void link(int v, int u) {
int pv = nt[v], pu = nt[u];
// bool gd = false;
// if ((v == 2) && (u == 4)) {
// cerr << "! " << pv << " " << pu << " -> ";
// for (auto& i : s[pu]) {
// cerr << (i.second + 1) << " ";
// }
// cerr << "\n";
// gd = true;
// }
if ((int)(s[pv].size()) < (int)(s[pu].size())) {
swap(pv, pu);
swap(v, u);
}
// if (gd == true) {
// cerr << (v + 1) << " " << (u + 1) << " " << pv << " " << pu << "\n";
// }
for (auto& i : s[pu]) {
int ost = n - i.first;
int f1 = i.first, f2, f3;
auto it = s[pv].upper_bound({ost / 2, -1});
int cnt = 0;
while ((cnt < 2) && (it != s[pv].begin())) {
++cnt;
--it;
}
cnt = 0;
while ((cnt < 4) && (it != s[pv].end())) {
f2 = (*it).first;
f3 = ost - (*it).first;
upd(f1, f2, f3);
++cnt;
++it;
}
}
for (auto& i : s[pu]) {
nt[i.second] = pv;
s[pv].insert(i);
}
nt[u] = nt[pu] = pv;
}
void dfs(int v, int pr) {
sz[v] = 1;
for (auto& u : g[v]) {
if (u == pr) {
continue;
}
dfs(u, v);
sz[v] += sz[u];
link(v, u);
}
if ((s[nt[v]].empty() == false) && (v != 0)) {
int f1 = n - sz[v], f2, f3;
int ost = sz[v];
auto it = s[nt[v]].upper_bound({ost / 2, -1});
int cnt = 0;
while ((cnt < 2) && (it != s[nt[v]].begin())) {
++cnt;
--it;
}
cnt = 0;
while ((cnt < 4) && (it != s[nt[v]].end())) {
// cerr << "! " << (v + 1) << " " << (*it).first << " " << ((*it).second + 1) << "\n";
f2 = (*it).first;
f3 = ost - (*it).first;
upd(f1, f2, f3);
// cerr << "\n";
++cnt;
++it;
}
}
s[nt[v]].insert({sz[v], v});
// cerr << (v + 1) << " " << nt[v] << "\n";
// for (auto& i : s[nt[v]]) {
// cerr << (i.second + 1) << " ";
// }
// cerr << "\n";
// cerr << "\n";
}
int main() {
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#ifdef _LOCAL
in("inD.txt");
out("outD.txt");
#endif
cin >> n;
for (int i = 0; i < n; ++i) {
nt[i] = i;
}
for (int i = 1; i < n; ++i) {
int v, u;
cin >> v >> u;
--v, --u;
g[v].push_back(u);
g[u].push_back(v);
}
ans = -1;
dfs(0, -1);
cout << ans << "\n";
return 0;
}
