#include <bits/stdc++.h>
using namespace std;
#ifdef DEBUG
#include "../Library/debug.h"
#else
#define dbg(x...)
#endif
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pi;
typedef pair<ll, ll> pl;
typedef vector<int> vi;
typedef vector<bool> vb;
typedef vector<ll> vl;
typedef vector<pi> vpi;
typedef vector<pl> vpl;
#define FOR(i, a, b) for (int i = (a); i < (b); ++i)
#define F0R(i, a) for (int i = 0; i < (a); ++i)
#define FORd(i, a, b) for (int i = (b) - 1; i >= (a); --i)
#define F0Rd(i, a) for (int i = (a) - 1; i >= 0; --i)
#define trav(a, x) for (auto& a : x)
#define f first
#define s second
#define pb push_back
#define sz(x) (int)(x).size()
#define all(x) x.begin(), x.end()
const char nl = '\n';
const int INF = 1e9;
const int MOD = 1e9 + 7;
int n;
vector<vi> adj;
vi pa;
struct DSU{
vi p;
vi sz;
DSU(int n){
p.resize(n);
F0R(i,n)p[i]=i;
sz.resize(n);
F0R(i,n)sz[i]=1;
}
int find(int a){
return p[a]==a?a:p[a]=find(p[a]);
}
bool merge(int a, int b){
int pa=find(a);
int pb=find(b);
if(pa==pb)
return false;
if(sz[pa]<sz[pb])
swap(pa,pb);
sz[pa]+=sz[pb];
p[pb]=pa;
return true;
}
};
void dfs(int v,int p){
pa[v]=p;
trav(u,adj[v]){
if(u==p)continue;
dfs(u,v);
}
}
int dp[(int)1e5][2][2][2][2];
int rt,sp;
int f(int v,int cv,int cf,int cr,int cs){
if(~dp[v][cv][cf][cr][cs]) return dp[v][cv][cf][cr][cs];
bool good=true;
if(v==rt&&cr!=cv) good=false;
if(v==sp&&cv!=cs) good=false;
if(v==sp&&cr&&cf) good=false;
if(!good) return dp[v][cv][cf][cr][cs]=1e9;
bool ccv=true; // next node to color
if(cf)ccv=false;
if(v==sp&&cr)ccv=false;
if(v==rt&&cs)ccv=false;
int cnt=cv;
trav(u,adj[v]){
if(u==pa[v]) continue;
cnt+=f(u,0,cv,cr,cs);
}
int res=1e9;
if(ccv){
trav(u,adj[v]){
if(u==pa[v])continue;
res=min(res,cnt-f(u,0,cv,cr,cs)+f(u,1,cv,cr,cs));
}
}
else{
res=min(res,cnt);
}
return dp[v][cv][cf][cr][cs]=res;
}
void solve(){
cin>>n;
memset(dp,-1,sizeof dp);
adj.resize(n);
pa.resize(n);
DSU dsu(n);
F0R(i,n){
int a,b;
cin>>a>>b;
a--,b--;
if(!dsu.merge(a,b)){
rt=a;
sp=b;
}
else{
adj[a].pb(b);
adj[b].pb(a);
}
}
dfs(rt,rt);
int ans=1e9;
F0R(i,2)F0R(j,2){
dbg(f(rt,i,0,i,j),i,j);
ans=min(ans,f(rt,i,0,i,j));
}
if(ans==(int)1e9)
cout<<-1<<nl;
else cout<<ans<<nl;
}
int32_t main(){
ios::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
int TC = 1;
// cin >> TC;
while(TC--){
solve();
}
return 0;
}
