bzoj2060

#include<bits/stdc++.h>
using namespace std;
const int N = 50010;
int n,cnt = 1;
int head[N], dp[N][2];
struct edge {
    int nxt, to;
} e[N << 1];
inline void link(int u, int v)
{
    e[++cnt].nxt = head[u];
    head[u] = cnt;
    e[cnt].to = v;
}
void dfs(int u, int last)
{
    int sum_0 = 0, sum_1 = 0;
    for(int i = head[u]; i; i = e[i].nxt)
    {
        if(e[i].to == last) continue;
        dfs(e[i].to, u);
        sum_0 += dp[e[i].to][0];
        sum_1 += dp[e[i].to][1];
    }
    dp[u][0] = max(sum_0, sum_1 + 1);
    dp[u][1] = sum_0;
}
int main()
{
    scanf("%d", &n);
    for(int i = 1; i < n; ++i)
    {
        int u, v;
        scanf("%d%d", &u, &v);
        link(u, v);
        link(v, u);
    }
    dfs(1, 0);
    printf("%d\n", dp[1][0]);
    return 0;
}