#include <iostream>
#include <cstdio>
#include <cmath>
#include <vector>
#include <cstring>
#include <algorithm>
#include <string>
#include <set>
#include <ctime>
#include <queue>
#include <map>
#include <sstream>#define CL(arr, val)    memset(arr, (val), sizeof(arr))
#define REP(i, n)       for((i) = 0; (i) < (n); ++(i))
#define FOR(i, l, h)    for((i) = (l); (i) <= (h); ++(i))
#define FORD(i, h, l)   for((i) = (h); (i) >= (l); --(i))
#define L(x)    (x) << 1
#define R(x)    (x) << 1 | 1
#define MID(l, r)   ((l) + (r)) >> 1
#define Min(x, y)   (x) < (y) ? (x) : (y)
#define Max(x, y)   (x) < (y) ? (y) : (x)
#define E(x)    (1 << (x))
#define iabs(x)  ((x) > 0 ? (x) : -(x))typedef long long LL;
const double eps = 1e-12;
const int inf = 10000;  using namespace std;const int N = 110;struct node {int to;int next;
} g[N<<2];    int head[N], t;bool vis[N];
int f[N][3];void init() {CL(head, -1); t = 0;
}void add(int u, int v) {g[t].to = v; g[t].next = head[u]; head[u] = t++;
}void dfs(int t) {int i, j, k, v, sum = 0, tmp, n;vector<int> ch;for(i = head[t]; i != -1; i = g[i].next) {v = g[i].to;if(!vis[v]) {vis[v] = true;dfs(v);sum += f[v][0];ch.push_back(v);}}n = ch.size();if(n == 0) {//printf("%d here!\n", t);f[t][0] = inf;f[t][1] = 0;f[t][2] = inf;return ;}f[t][1] = min(inf, sum);f[t][0] = f[t][2] = inf;for(i = 0; i < n; ++i) {v = ch[i];f[t][2] = min(f[t][2], sum - f[v][0] + min(f[v][1], f[v][2]));f[t][0] = min(f[t][0], sum - f[v][0] + f[v][2] + 1);}for(i = 0; i < n; ++i) {v = ch[i];for(j = 0; j < n; ++j) {if(i == j)  continue;k = ch[j];tmp = sum - f[v][0] - f[k][0] + min(f[v][1], f[v][2]) + min(f[k][1], f[k][2]);f[t][0] = min(f[t][0], tmp + 1);}}
}int main() {//freopen("data.in", "r", stdin);int n, x, y, i;while(~scanf("%d", &n)) {init();for(i = 1; i < n; ++i) {scanf("%d%d", &x, &y);add(x, y); add(y, x);}CL(vis, false); vis[1] = true;dfs(1);//for(i = 1; i <= n; ++i) printf("%d | %-11d %-11d %-11d\n", i, f[i][0], f[i][1], f[i][2]);if(f[1][0] >= inf)  puts("-1");else    printf("%d\n", f[1][0]);}return 0;
}