#include<bits/stdc++.h>
#define int long long
#define il inline
namespace things{
	il int rd(){
		int f = 1, x = 0;
		char ch = getchar();
		while(ch < '0' || ch > '9'){
			if (ch == '-' ) f = -1;
			ch = getchar();
		}
		while(ch >= '0' && ch <= '9'){
			x = x * 10 + ch - '0';
			ch = getchar();
		}
		return x * f;
	}
	il int max(int x, int y){
		return std::max(x, y);
	}
	il int min(int a, int b){
		return std::min(a, b);
	}
}
using namespace things;
using namespace std;

const int N = 1e6 + 5;
int v[N << 1], nxt[N << 1], head[N];
int w[N << 1];
int n, m, tot, cur;
bool key[N];
int dfn[N], seq[N], st[N];
int s[N], f[N], dist[N];

void add(int x, int y){
	v[++tot] = y; w[tot] = 1; nxt[tot] = head[x]; head[x] = tot;
}

struct Sgt{
	int mx[N << 2], tag[N << 2];
	void update(int o){
		mx[o] = max(mx[o << 1], mx[o << 1 | 1]);
	}
	void pushdown(int o){
		if (tag[o]){
			mx[o << 1] += tag[o];
			mx[o << 1 | 1] += tag[o];
			tag[o << 1] += tag[o];
			tag[o << 1 | 1] += tag[o];
			tag[o] = 0;
		}
	}
	void build(int o, int l, int r){
		if (l == r){
			mx[o] = dist[seq[l]];
			return;
		}
		int mid = (l + r) >> 1;
		build(o << 1, l, mid);
		build(o << 1 | 1, mid + 1, r);
		update(o);
	}
	void add(int o, int lb, int rb, int l, int r, int d){
		if (l > rb || r < lb) return;
		if (l <= lb && r >= rb){
			mx[o] += d;
			tag[o] += d;
			return;
		}
		pushdown(o);
		int mid = (lb + rb) >> 1;
		add(o << 1, lb, mid, l, r, d);
		add(o << 1 | 1, mid + 1, rb, l, r, d);
		update(o);
	}
	void add(int l, int r, int d){
		if (l <= r) add(1, 1, m, l, r, d);
	}
	int query(int o, int lb, int rb, int l, int r){
		if (l > rb || r < lb) return 0;
		if (l <= lb && r >= rb) return mx[o];
		pushdown(o);
		int mid = (lb + rb) >> 1;
		return max(query(o << 1, lb, mid, l, r), query(o << 1 | 1, mid + 1, rb, l, r));
	}
}sgt;

void dfs(int x, int fa){
	if (key[x]){
		s[x] = 1;
		dfn[x] = ++cur;
		seq[cur] = x;
	}
	for (int i = head[x]; i; i = nxt[i]){
		if (v[i] != fa){
			dist[v[i]] = dist[x] + w[i];
			dfs(v[i], x);
			s[x] += s[v[i]];
			if (s[v[i]]) f[x] += f[v[i]] + 2ll * w[i];
		}
	}
	if (s[x]) st[x] = cur - s[x] + 1;
}

signed main(){
	n = rd(), m = rd();
	for (int i = 1; i <= m; i++){
		int x;
		x = rd();
		key[x] = 1;
	}
	for (int i = 1; i <= n - 1; i++){
		int x, y;
		x = rd(), y = rd();
		add(x, y);
		add(y, x);
	}
	dfs(1, 0);
	sgt.build(1, 1, m);
	cout << f[1] - sgt.query(1, 1, m, 1, m);
	return 0;
}