#include <bits/stdc++.h>
using namespace std;
#define SPEED ios_base::sync_with_stdio(0); cin.tie(NULL); cout.tie(NULL);
#define pb push_back
#define ALL(x) x.begin(), x.end()
#define sz(x) (intt)x.size()
#define intt long long
#define endl "\n"
const intt mod = 1e9 + 7;
const intt mxN = 200001;
const intt mxA = 5e4 + 31;
const intt inf = 1e9;
set<intt> graph[mxN];
vector<intt> color(mxN), cycle;
intt n, root, special, dp[mxN][2][2];
bool find_cycle(intt node, intt parent) {
color[node] = 1;
cycle.pb(node);
for(auto u : graph[node]) {
if(!color[u]) {
if(find_cycle(u, node)) return true;
} else if(u != parent) {
cycle.pb(u);
return true;
}
}
cycle.pop_back();
return false;
}
void dfs(intt node, intt parent, intt rc, intt sc) {
intt sum1 = 0, sum2 = 0;
for(auto u : graph[node]) {
if(u != parent) {
dfs(u, node, rc, sc);
sum1 += dp[u][0][0];
sum2 += dp[u][0][1];
}
}
dp[node][1][0] = dp[node][0][0] = inf;
for(auto u : graph[node]) {
if(u != parent) {
dp[node][1][0] = min(dp[node][1][0], sum2 - dp[u][0][1] + dp[u][1][1] + 1);
dp[node][0][0] = min(dp[node][0][0], sum1 - dp[u][0][0] + dp[u][1][0]);
}
}
dp[node][0][1] = sum1;
dp[node][1][1] = sum2 + 1;
if(dp[node][1][1] > inf) dp[node][1][1] = inf;
if(dp[node][1][0] > inf) dp[node][1][0] = inf;
if(node == special) {
dp[node][sc^1][1] = dp[node][sc^1][0] = inf;
if(rc) {
dp[node][sc][1] = inf;
if(sc == 0) {
dp[node][sc][0] = sum1;
} else{
dp[node][sc][0] = sum2 + 1;
}
}
}
if(node == root) {
dp[node][rc^1][1] = dp[node][rc^1][0] = inf;
}
}
void solve() {
intt n;
cin >> n;
for(intt i = 1; i <= n; i++) {
intt a, b;
cin >> a >> b;
graph[a].insert(b);
graph[b].insert(a);
}
find_cycle(1, 0);
reverse(ALL(cycle));
root = cycle[0], special = cycle[1];
// cout << root << " " << special << endl;
graph[root].erase(special);
graph[special].erase(root);
intt ans = inf;
for(intt i = 0; i < 2; i++) {
for(intt j = 0; j < 2; j++) {
dfs(root, 0, i, j);
ans = min(ans, dp[root][i][j]);
}
}
if(ans >= inf) {
ans = -1;
}
cout << ans << endl;
}
signed main() {
SPEED;
intt tst = 1;
// cin >> tst;
while (tst--)
solve();
}
