#include <bits/stdc++.h>
using namespace std;
const int MAXN = (int) 1e5;
const int INF = 0x3f3f3f3f;
class dsu {
private: vector<int> p, rank, sz;
public:
dsu(int n) {
p.assign(n, -1);
rank.assign(n, 0);
sz.assign(n, 1);
}
int root(int x) {
if (p[x] == -1) return x;
return p[x] = root(p[x]);
}
bool connected(int x, int y) {
return root(x) == root(y);
}
void connect(int x, int y) {
x = root(x); y = root(y);
if (x != y) {
if (rank[x] > rank[y]) p[y] = x, sz[x] += sz[y];
else {
p[x] = y;
sz[y] += sz[x];
if (rank[x] == rank[y]) rank[y]++;
}
}
}
int size(int x) {
return sz[root(x)];
}
};
int n, root, special;
vector< vector<int> > g;
long long dp[MAXN + 1][2][2][2][2];
void dfs(int u, int p) {
for (auto &v : g[u]) if (v != p) dfs(v, u);
for (int val = 0; val < 2; val++) {
for (int up = 0; up < 2; up++) {
for (int rt = 0; rt < 2; rt++) {
for (int sp = 0; sp < 2; sp++) {
if (u == special && rt && up) continue;
if (u == root && rt != val) continue;
if (u == special && sp != val) continue;
if (p == root && rt != up) continue;
if (u == root && up) continue;
bool found = (u == root && sp) || (u == special && rt) || up;
long long tmp = val;
for (auto &v : g[u]) if (v != p) tmp += dp[v][0][val][rt][sp];
if (found) dp[u][val][up][rt][sp] = tmp;
else for (auto &v : g[u]) if (v != p) dp[u][val][up][rt][sp] = min((long long) dp[u][val][up][rt][sp], tmp - dp[v][0][val][rt][sp] + dp[v][1][val][rt][sp]);
}
}
}
}
}
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
cin >> n;
g.resize(n + 1);
dsu g2(n + 1);
for (int i = 0; i < n; i++) {
int u, v;
cin >> u >> v;
if (g2.connected(u, v)) root = u, special = v;
else {
g[u].push_back(v);
g[v].push_back(u);
}
g2.connect(u, v);
}
for (int u = 1; u <= n; u++) for (int val = 0; val < 2; val++) for (int up = 0; up < 2; up++) for (int rt = 0; rt < 2; rt++) for (int sp = 0; sp < 2; sp++) dp[u][val][up][rt][sp] = INF;
dfs(root, -1);
long long ans = INF;
for (int val = 0; val < 2; val++) for (int up = 0; up < 2; up++) for (int rt = 0; rt < 2; rt++) for (int sp = 0; sp < 2; sp++) ans = min(ans, dp[root][val][up][rt][sp]);
if (ans == INF) cout << -1 << '\n';
else cout << ans << '\n';
return 0;
}
