//#pragma GCC optimize("O3,unroll-loops")
//#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#include <bits/stdc++.h>
#define int long long
#define ll long long
#define fi first
#define se second
#define pb push_back
#define all(lmao) lmao.begin(), lmao.end()
using namespace std;
typedef pair<int,int> pii;
typedef tuple<int,int,int> tp;
const int N = 2e5 + 5;
const int oo = 1e9 + 1;
const int mod = 1e9 + 7;
//const ll oo = 5e18;
int n, d[N], X[N], Y[N], fl[N], f[N][5][5], ans, A, B, sA, sB;
vector<int> p[N], g[N];
void dfs(int u,int v){
fl[u] = 1;
for(auto j : p[u]){
if(j == v) continue;
if(fl[j]){
A = u;
B = j;
continue;
}
g[u].pb(j);
g[j].pb(u);
dfs(j, u);
}
}
void solve(int u,int v){
f[u][0][0] = f[u][1][1] = f[u][1][0] = f[u][0][1] = oo;
int sum = 0, w = 0;
f[u][0][0] = f[u][1][0] = 0;
for(auto j : g[u]){
if(j == v) continue;
solve(j, u);
f[u][0][0] += f[j][0][1]; // 0
sum += f[j][0][1]; // 1
f[u][1][0] += f[j][0][0];
w += f[j][0][0];
}
f[u][1][0]++;
f[u][1][0] = min(f[u][1][0], oo);
for(auto j : g[u]){
if(j == v) continue;
// cerr << j << " " << sum << " "<< f[j][0][1] << " " << f[j][1][1] << " " << f[u][0][1] << " y\n";
f[u][0][1] = min(f[u][0][1], sum - f[j][0][1] + f[j][1][1]);
f[u][1][1] = min(f[u][1][1], 1 + w - f[j][0][0] + f[j][1][0]);
}
// cerr << u << " " << sum << " " << w << " " << f[u][0][0] << " " << f[u][0][1] << " " << f[u][1][0] << " " << f[u][1][1] << " bf\n";
f[u][1][1] = min(f[u][1][1], oo);
if((int)g[u].size() == 1 && u != A){
f[u][0][0] = 0;
f[u][0][1] = oo;
f[u][1][0] = 1;
f[u][1][1] = oo;
}
if(u == A){
if(sA == 1 && sB == 1) f[u][1][1] = f[u][1][0];
else if(sA == 0 && sB == 1) f[u][0][1] = f[u][0][0];
}else if(u == B){
if(sA == 1 && sB == 1){
f[u][1][1] = f[u][1][0];
f[u][0][1] = f[u][0][0] = f[u][1][0] = oo;
}else if(sA == 1 && sB == 0){
f[u][0][1] = f[u][0][0];
f[u][0][0] = f[u][1][1] = f[u][1][0] = oo;
}else if(sA == 0 && sB == 1){
f[u][0][0] = f[u][0][1] = oo;
}else if(sA == 0 && sB == 0){
f[u][1][0] = f[u][1][1] = oo;
}
}
// cerr << u << " " << sum << " " << w << " " << f[u][0][0] << " " << f[u][0][1] << " " << f[u][1][0] << " " << f[u][1][1] << " j\n";
}
signed main(){
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define task "v"
if(fopen(task ".inp","r")){
freopen(task ".inp","r",stdin);
freopen(task ".out","w",stdout);
}
cin >> n;
vector<int> vr;
for(int i = 1; i <= n; i ++){
cin >> X[i] >> Y[i];
p[Y[i]].pb(X[i]);
p[X[i]].pb(Y[i]);
}
dfs(1, 0);
// cerr << A << " " << B << "\n";
ans = oo;
for(int i = 0; i <= 1; i ++){
for(int j = 0; j <= 1; j ++){
sA = i, sB = j;
solve(A, 0);
// cerr << " " << sA << " " << sB << " " << f[A][sA][1] << " t\n";
ans = min(ans, f[A][sA][1]);
}
}
if(ans <= n) cout << ans;
else cout << -1;
}
