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//============================================================================
// Name        : tests.cpp
// Author      :
// Version     :
// Copyright   : Your copyright notice
// Description : Hello World in C++, Ansi-style
//============================================================================

#include <iostream>
#include <list>
using namespace std;

class Changer
{
public:
	bool start;
	int value;

	Changer(int v, bool s){
		start = s;
		value = v;
	}

};


struct compare {
    bool operator()(Changer const * a, Changer const * b) {
        return a->value < b->value;
    }
};

class Miasto
{
public:

	bool zagranico;
	int firstValue;
	int secondValue;
	bool odwiedzoned;

	std::list<Miasto*> sasiedzi;

	Miasto()
	{
		firstValue = 0;
		secondValue = 0;
		zagranico = 0;
		odwiedzoned = 0;
	}

	void addSasiad(Miasto* m)
	{
		sasiedzi.push_front(m);
	}


	long long getResult(Miasto* last)
	{
		if(zagranico || odwiedzoned)
		{
			return 0;
		}

		odwiedzoned = 1;
		long long result=0;

		std::list<Changer*> changers;

		long long currentResult = 0;
		long long bestResult = 0;
		int bestResultStart = 0;
		int long bestResultEnd = 0;

		int mniejsze =0;
		int wieksze =0;

		for(auto it=sasiedzi.begin(); it!= sasiedzi.end(); ++it)
		{
			result += (*it)->getResult(this);

			if((*it) != last)
			{
				Changer* changer1 = new Changer((*it)->firstValue,true);
				Changer* changer2 = new Changer((*it)->secondValue,false);
				changers.push_front(changer1);
				changers.push_front(changer2);
				wieksze++;

				currentResult += (*it)->firstValue;
			}
		}

		bestResult = currentResult;

		changers.sort(compare());

		int lastValue=0;
		for (auto it=changers.begin(); it!= changers.end(); ++it)
		{
			//cout<<wieksze<<" "<<mniejsze<<" "<<(*it)->value<<" "<<lastValue<<endl;
			currentResult -= wieksze * ((*it)->value - lastValue);
			currentResult += mniejsze * ((*it)->value - lastValue);

			lastValue = (*it)->value;

			if(currentResult < bestResult)
			{
				bestResult = currentResult;
				bestResultStart = (*it)->value;
				bestResultEnd = (*it)->value;
			}
			else if(currentResult == bestResult)
			{
				bestResultEnd = (*it)->value;
			}


			if((*it)->start)wieksze--;
			else
				mniejsze++;
		}

		result+=bestResult;
		firstValue = bestResultStart;
		secondValue = bestResultEnd;

		return result;
	}


};

Miasto** miasta;



int main()
{
	std::ios_base::sync_with_stdio(false);
	int n,m;
	cin>>n>>m;

	if(m==n)
	{
		cout<<0<<endl;
		return 0;
	}

	miasta = new Miasto*[n+1];
	for(int k=1; k<=n;k++)
	{
		miasta[k] = new Miasto();

	}

	int a, b;
	for(int k=0; k< n-1;k++)
	{
		cin>>a>>b;
		miasta[a]->addSasiad(miasta[b]);
		miasta[b]->addSasiad(miasta[a]);
	}
	int c;
	for(int k=1;k<=m;k++)
	{
		cin>>c;
		miasta[k]->firstValue = c;
		miasta[k]->secondValue = c;
		miasta[k]->zagranico = true;
	}

	long long result = miasta[m+1]->getResult(NULL);

	cout<<result<<endl;
}