#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 endl "\n"
#define ALL(x) x.begin(), x.end()
#define intt long long
const intt mxN = 2e5 + 5, L = 20, mxA = 1e6 + 35, inf = 1e9 + 7;
vector<intt> graph[mxN];
intt dp[mxN][2][2] = {inf};
void dfs(intt node, intt parent, intt root, intt root_color, intt special, intt special_color) {
intt sum1 = 0, sum2 = 0;
for(auto u : graph[node]) {
if(u != parent) {
dfs(u, node, root, root_color, special, special_color);
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) {
for(intt c = 0; c <= 1; c++) {
dp[node][c][0] = min(dp[node][c][0], (c == 0 ? sum1 : sum2) - dp[u][0][c] + dp[u][1][c] + (c == 1));
}
}
}
dp[node][0][1] = min(inf, sum1);
dp[node][1][1] = min(inf, sum2 + 1);
if(node == special) {
dp[node][special_color ^ 1][0] = dp[node][special_color ^ 1][1] = inf;
if(root_color) {
dp[node][special_color][1] = inf;
if(special_color == 0) {
dp[node][special_color][0] = sum1;
} else {
dp[node][special_color][0] = sum2 + 1;
}
}
}
if(node == root) {
dp[node][root_color^1][0] = dp[node][root_color^1][1] = inf;
}
}
intt root, special;
vector<intt> color(mxN), cycle;
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 solve() {
intt n;
cin >> n;
for(intt i = 1; i <= n; i++) {
intt a, b;
cin >> a >> b;
graph[a].pb(b);
graph[b].pb(a);
}
find_cycle(1, 0);
reverse(ALL(cycle));
root = cycle[0]; special = cycle[1];
for(intt i = 0; i < graph[root].size(); i++) {
if(graph[root][i] == special) {
graph[root].erase(graph[root].begin() + i); break;
}
}
for(intt i = 0; i < graph[special].size(); i++) {
if(graph[special][i] == root) {
graph[special].erase(graph[special].begin() + i); break;
}
}
intt ans = inf;
for(intt i = 0; i < 2; i++) {
for(intt j = 0; j < 2; j++) {
dfs(root, 0, root, i, special, j);
// for(intt k = 1; k <= n; k++) {
// for(intt a = 0; a < 2; a ++ ) {
// for(intt b = 0; b < 2; b++) {
// cout << dp[k][a][b] << " ";
// }
// cout << endl;
// }
// cout << endl;
// }
// cout << dp[root][i][j] << " ";
ans = min(ans, dp[root][i][j]);
}
}
cout << (ans >= inf ? -1 : ans) << endl;
}
int main() {
SPEED;
int tst = 1;
// cin >> tst;
while (tst--) {
solve();
}
return 0;
}
