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import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.*;

public class roz {
    BufferedReader rd;

    roz() throws IOException {
        rd = new BufferedReader(new InputStreamReader(System.in));
        compute();
    }

    private void compute() throws IOException {
        int[] a = intarr();
        int n = a[0];
        int m = a[1];
        List[] e = new List[n];
        for(int i=0;i<e.length;i++) {
            e[i] = new ArrayList(1);
        }
        for(int i=0;i<n-1;i++) {
            a = intarr();
            int u = a[0]-1;
            int v = a[1]-1;
            e[u].add(v);
            e[v].add(u);
        }
        final double[] lo = new double[n];
        final double[] hi = new double[n];
        int[] done = new int[n];
        for(int i=0;i<m;i++) {
            lo[i] = pint();
            hi[i] = lo[i];
        }
        Set<Integer> ok = new HashSet<>();
        if(m == n-1) {
            ok.add(m);
        } else {
            Set<Integer> nk = new HashSet<>();
            for(int i=0;i<m;i++) {
                for(Integer v: (List<Integer>)e[i]) {
                    if(v >= m) {
                        if(!ok.contains(v) && !nk.contains(v)) {
                            int cnt = 0;
                            int cnt2 = 0;
                            for(Integer u: (List<Integer>)e[v]) {
                                if(u>=m) {
                                    cnt++;
                                } else {
                                    cnt2++;
                                }
                            }
                            done[v] = cnt2;
                            if(cnt == 1) {
                                ok.add(v);
                            } else {
                                nk.add(v);
                            }
                        }
                    }
                }
            }
        }
        boolean[] p = new boolean[n];
        for(int i=0;i<m;i++) {
            p[i] = true;
        }
        Comparator<Integer> byR = new Comparator<Integer>() {
            @Override
            public int compare(Integer a, Integer b) {
                return Double.compare(hi[a] + lo[a],hi[b] + lo[b]);
            }
        };
        Queue<Integer> q = new ArrayDeque<>(ok);
        Integer v = 0;
        while(!q.isEmpty()) {
            v = q.poll();
            List<Integer> ne = new ArrayList<>();
            for(Integer u: (List<Integer>)e[v]) {
                if(p[u]) {
                    ne.add(u);
                } else {
                    done[u]++;
                    if(e[u].size() - done[u] == 1) {
                        q.add(u);
                    }
                }
            }
            Integer[] arr = ne.toArray(new Integer[ne.size()]);
            Arrays.sort(arr, byR);
            if(arr.length%2==1) {
                int mid = arr.length/2;
                lo[v] = lo[arr[mid]];
                hi[v] = hi[arr[mid]];
            } else {
                int x = arr.length/2-1;
                int y = arr.length/2;
                double[] c = md(lo[arr[x]],hi[arr[x]],lo[arr[y]],hi[arr[y]]);
                lo[v] = c[0];
                hi[v] = c[1];
            }
            p[v] = true;
        }
        long minSum = Long.MAX_VALUE;
        Integer start = v;
        for(int i=0;i<2;i++) {
            double[] fn = new double[n];
            fn[start] = i==0?lo[start]:hi[start];
            p = new boolean[n];
            q = new ArrayDeque<>();
            q.add(start);
            double sum = 0;
            while(!q.isEmpty()) {
                v = q.poll();
                p[v] = true;
                for(Integer u: (List<Integer>)e[v]) {
                    if(!p[u]) {
                        p[u] = true;
                        if(fn[v] < lo[u]) {
                            sum += lo[u] - fn[v];
                            fn[u] = lo[u];
                        } else if(fn[v] > hi[u]) {
                            sum += fn[v] - hi[u];
                            fn[u] = hi[u];
                        } else {
                            fn[u] = fn[v];
                        }
                        q.add(u);
                    }
                }
            }
            long cur = Math.round(Math.floor(sum+0.01));
            minSum = Math.min(minSum, cur);
        }
        out(minSum);
    }

    private double[] md(double x1, double x2, double y1, double y2) {
        double[] res;
        if(x2 >= y1 && y2 >= x1) {
            if(x1 <= y1) {
                if(x2 >= y2) {
                    res = new double[] { y1, y2 };
                } else {
                    res = new double[] { y1, x2 };
                }
            } else {
                if(x2 < y2) {
                    res = new double[] { x1, x2 };
                } else {
                    res = new double[] { x1, y2 };
                }
            }
        } else if(x1 > y2) {
            res = new double[] { y2, x1 };
        } else {
            res = new double[] { x2, y1 };
        }
        return res;
    }

    private int pint() throws IOException {
        return pint(rd.readLine());
    }

    private int pint(String s) {
        return Integer.parseInt(s);
    }

    private int[] intarr() throws IOException {
        return intarr(rd.readLine());
    }

    private int[] intarr(String s) {
        String[] q = split(s);
        int n = q.length;
        int[] a = new int[n];
        for(int i=0;i<n;i++) {
            a[i] = Integer.parseInt(q[i]);
        }
        return a;
    }

    public String[] split(String s) {
        if(s == null) {
            return new String[0];
        }
        int n = s.length();
        int start = -1;
        int end = 0;
        int sp = 0;
        boolean lastWhitespace = true;
        for(int i=0;i<n;i++) {
            char c = s.charAt(i);
            if(isWhitespace(c)) {
                lastWhitespace = true;
            } else {
                if(lastWhitespace) {
                    sp++;
                }
                if(start == -1) {
                    start = i;
                }
                end = i;
                lastWhitespace = false;
            }
        }
        if(start == -1) {
            return new String[0];
        }
        String[] res = new String[sp];
        int last = start;
        int x = 0;
        lastWhitespace = true;
        for(int i=start;i<=end;i++) {
            char c = s.charAt(i);
            boolean w = isWhitespace(c);
            if(w && !lastWhitespace) {
                res[x++] = s.substring(last,i);
            } else if(!w && lastWhitespace) {
                last = i;
            }
            lastWhitespace = w;
        }
        res[x] = s.substring(last,end+1);
        return res;
    }

    private boolean isWhitespace(char c) {
        return c==' ' || c=='\t';
    }

    private static void out(Object x) {
        System.out.println(x);
    }

    public static void main(String[] args) throws IOException {
        new roz();
    }
}