#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N = 1e5 + 10, MOD = 998244353;
#define int long long
int n;
vector<int> g[N];
vector<pair<int, int>> e;
int used[N], rt, sp, dp[N][2][2][2][2];
void dfs(int v, int pr = -1)
{
used[v] = 1;
for (int to : g[v])
{
if (to == pr)
continue;
if (!used[to])
{
dfs(to, v);
}
else
{
sp = v;
rt = to;
}
}
}
void fill(int v, int val)
{
for (int me = 0; me <= 1; me++)
{
for (int up = 0; up <= 1; up++)
{
for (int r = 0; r <= 1; r++)
{
for (int s = 0; s <= 1; s++)
{
dp[v][me][up][r][s] = val;
}
}
}
}
}
int go(int v, int me, int up, int r, int s, int pr = -1)
{
if (dp[v][me][up][r][s] != -1)
{
return dp[v][me][up][r][s];
}
int res = 1e9;
dp[v][me][up][r][s] = 1e9;
if (v == sp && me != s)
return dp[v][me][up][r][s];
if (v == rt && r != me)
return dp[v][me][up][r][s];
if (v == sp && up && r)
return dp[v][me][up][r][s];
bool is_black = 0;
if (up)
is_black = 1;
if (v == sp && r)
is_black = 1;
if (v == rt && s)
is_black = 1;
int sum = me;
for (int to : g[v])
{
if (to == pr)
continue;
sum += go(to, 0, me, r, s, v);
}
if (is_black)
{
res = min(res,sum);
}
else
{
for (int to : g[v])
{
if (to == pr){
continue;
}
res = min(res, sum - go(to, 0, me, r, s, v) + go(to, 1, me, r, s, v));
}
}
return dp[v][me][up][r][s] = res;
}
void test()
{
cin >> n;
for (int i = 1; i <= n; i++)
{
int x, y;
cin >> x >> y;
g[x].push_back(y);
g[y].push_back(x);
e.push_back({x, y});
}
dfs(1);
for (int i = 1; i <= n; i++)
{
g[i].clear();
}
for (auto [x, y] : e)
{
if ((x == rt && y == sp) || (x == sp && y == rt))
continue;
g[x].push_back(y);
g[y].push_back(x);
}
int res = 1e9;
for (int i = 1; i <= n; i++)
{
fill(i, -1);
}
// cout << rt << ' ' << sp << '\n';
for (int me = 0; me <= 1; me++)
{
for (int s = 0; s <= 1; s++)
{
res = min(res, go(rt, me, 0, me, s));
}
}
if (res == 1e9)
res = -1;
cout << res;
}
main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
int T = 1;
// cin >> T;
for (int i = 1; i <= T; i++)
{
test();
}
}
