#include <bits/stdc++.h>
#define INF 10000
#define pb push_back
using namespace std;
const int N = 105;
int n, x, y, sum;
vector<int> Edge[N];
int dp[N][3];
bool vis[N];
void dfs(int x) {
    vis[x] = true, sum = 0;
    vector<int> son;
    for (int i : Edge[x]) {
        if (!vis[i]) {
            son.pb(i);
            dfs(i);
            sum += dp[i][0];
        }
    }
    if (son.size() == 0) {
        dp[x][0] = dp[x][2] = INF;
        dp[x][1] = 0;
        return;
    }
    dp[x][0] = dp[x][2] = INF;
    dp[x][1] = min(INF, sum);
    for (int i : son) {
        dp[x][2] = min(dp[x][2], sum - dp[i][0] + min(dp[i][1], dp[i][2]));
        dp[x][0] = min(dp[x][0], sum - dp[i][0] + dp[i][2] + 1);
    }
    for (int i : son) {
        for (int j : son) {
            if (i == j) continue;
            dp[x][0] = min(dp[x][0], sum - dp[i][0] - dp[j][0] + min(dp[i][1], dp[i][2]) + min(dp[j][1], dp[j][2]) + 1);
        }
    }
}
int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    cin >> n;
    for (int i = 1; i < n; i++) {
        cin >> x >> y;
        Edge[x].pb(y);
        Edge[y].pb(x);
    }
    dfs(1);
    if (dp[1][0] >= INF) {
        cout << dp[1][0] << '\n';
    } else {
        cout << "-1\n";
    }
}