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#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cmath>
#include<algorithm>
#include<vector>
#include<set>
#include<map>
#include<stack>
#include<queue>
#include<list>
#include<string>
#include<cstring>
#include<climits>

using namespace std;

#define PB push_back
#define MP make_pair
#define F first
#define S second
#define ALL(x) (x).begin(),(x).end()
#define SIZE(x) (int)(x).size()
#define SORT(x) sort((x).begin(),(x).end())
#define CLEAR(tab) memset(tab, 0, sizeof(tab))
#define REP(x, n) for(int x = 0; x < (n); x++)
#define FOR(x, b, e) for(int x = (b); x <= (e); x++)
#define FORD(x, b, e) for(int x = (b); x >= (e); x--)
#define VAR(v, n) __typeof(n) v = (n)
#define FOREACH(i, c) for(VAR(i, (c).begin()); i != (c).end(); ++i)
#define DEBUG(fmt, ...) fprintf(stderr, fmt, ##__VA_ARGS__)

const int MAX_BUF_SIZE = 16384;
char BUFOR[MAX_BUF_SIZE];
int BUF_SIZE, BUF_POS;
char ZZZ;
#define GET(ZZZ){ZZZ='a';if(BUF_POS<BUF_SIZE)ZZZ=BUFOR[BUF_POS++];\
else if(!feof(stdin)){BUF_SIZE=fread(BUFOR,1,MAX_BUF_SIZE,stdin);\
ZZZ=BUFOR[0];BUF_POS=1;}}
#define GI(WW){do{GET(ZZZ);}while(!isdigit(ZZZ));WW=ZZZ-'0';\
while(1){GET(ZZZ);if(!isdigit(ZZZ))break;WW=WW*10+(ZZZ-'0');}}
#define GC(WW){do{GET(ZZZ);}while(!isalpha(ZZZ));WW=ZZZ;}

//FAST IO

typedef long long int LL;
typedef pair<int,int> PII;
typedef vector<int> VI;

const int MXN = 2 * 500010;
const int C = 262144;
const LL INF = LLONG_MAX;

int n, m;
VI G[MXN];
bool vis[MXN];
PII res[MXN];
LL R;
LL sum[MXN][2];
LL cnt[MXN][2];

PII solve(vector<PII> &vec) {
	PII res = MP(2 * MXN, -2 * MXN);
	vector<PII> a;

	FOREACH(it, vec) {
		a.PB(MP(it -> F, 0) );
		a.PB(MP(it -> S, 1) );
	}

	SORT(a);

	int Q = SIZE(a);

	PII old = MP(0, 0);
	FOR(i, 1, Q) {
		PII p1 = a[i - 1];
		cnt[i][1] = cnt[i - 1][1] + (p1.S == 1);
		sum[i][1] = sum[i - 1][1] + (LL)(p1.F - old.F) * cnt[i - 1][1];
		old = p1;
	}

	sum[Q + 1][0] = cnt[Q + 1][0] = 0;
	old = MP(0, 0);
	FORD(i, Q, 1) {
		PII p1 = a[i - 1];
		cnt[i][0] = cnt[i + 1][0] + (p1.S == 0);
		sum[i][0] = sum[i + 1][0] + (LL)(old.F - p1.F) * cnt[i + 1][0];
		old = p1;
	}

	LL BEST = INF;
	FOR(i, 1, Q)
		if(BEST > sum[i][0] + sum[i][1]) {
			BEST = sum[i][0] + sum[i][1];
			res = MP(a[i - 1].F, a[i - 1].F);
		}
		else if(BEST == sum[i][0] + sum[i][1]) {
			res.F = min(res.F, a[i - 1].F);
			res.S = max(res.F, a[i - 1].F);
		}
	
	R += BEST;
	return res;
}


void dfs(int x) {
	vis[x] = 1;
	vector<PII> vec;
	FOREACH(it, G[x])
		if(!vis[*it]) {
			dfs(*it);
			vec.PB(res[*it]);
		}

	if(SIZE(G[x]) > 1)
		res[x] = solve(vec);
}

int main() {
	scanf("%d %d", &n, &m);

	FOR(i, 1, n - 1) {
		int a, b;
		scanf("%d %d", &a, &b);
		G[a].PB(b);
		G[b].PB(a);
	}

	FOR(i, 1, m) {
		int x;
		scanf("%d", &x);
		res[i] = MP(x, x);
	}

	if(n == 2) {
		printf("%d\n", abs(res[1].F - res[2].F) );
		return 0;
	}

	dfs(n);
	printf("%lld\n", R);
	return 0;
}