略。）
const int N = 10009;
int dp0[N], dp1[N], dp2[N];
VI adj[N]; bool vst[N];
int n;
void dfs(int u = 0){
vst[u] = true; int delta = INF; dp0[u] = 1;
#define v adj[u][i]
REP(i, SZ(adj[u])) if (!vst[v]){
dfs(v), dp0[u] += min(dp0[v], dp2[v]), dp2[u] += dp1[v];
if (dp0[v] <= dp1[v]) dp1[u] += dp0[v], delta = 0;
else dp1[u] += dp1[v], checkMin(delta, dp0[v] - dp1[v]);;
}
dp1[u] += delta;
}
int main(){
//freopen("in.txt", "r", stdin);
do {
int a, b; FOR_C(i, 1, _RD(n)) RD(a, b), --a, --b, adj[a].PB(b), adj[b].PB(a);
dfs(), OT(min(dp0[0], dp1[0])), RST(vst, dp0, dp1, dp2); REP(i, n) CLR(adj[i]);
} while (RD() != -1);
}
