#include<bits/stdc++.h>
using namespace std;
int n,k,a[200005],dep[200005],dfn[200005],d,minn[200005][20],lg[200005],f[200005],g[200005],l=1,r,now;
vector<int>e[200005];
set<pair<int,int> >s;
void dfs(int pos,int fa,vector<int>e[]){
  minn[dfn[pos]=++d][0]=fa,dep[pos]=dep[fa]+1;
  for(int i=0;i<e[pos].size();i++)if(e[pos][i]!=fa)dfs(e[pos][i],pos,e);
}
int cmp(int a,int b){
  return dfn[a]<dfn[b]?a:b;
}
void init(int s,vector<int>e[]){
  dfs(s,0,e);
  for(int i=2;i<=d;i++)lg[i]=lg[i>>1]+1;
  for(int j=1;1<<j<=d;j++)for(int i=1;i+(1<<j)-1<=d;i++)minn[i][j]=cmp(minn[i][j-1],minn[i+(1<<(j-1))][j-1]);
}
int lca(int u,int v){
  if(u==v)return u;
  u=dfn[u],v=dfn[v];
  if(u>v)swap(u,v);
  return u++,cmp(minn[u][lg[v-u+1]],minn[v-(1<<lg[v-u+1])+1][lg[v-u+1]]);
}
int dis(int u,int v){
  return dep[u]+dep[v]-2*dep[lca(u,v)];
}
void add(int x){
  if(x==1)return;
  s.insert(make_pair(dfn[x],x));
  set<pair<int,int> >::iterator it=s.find(make_pair(dfn[x],x)),pre=it,nxt=it;
  if(it==s.begin())pre=--s.end();
  else pre--;
  if(it==--s.end())nxt=s.begin();
  else nxt++;
  int t1=(*pre).second,t2=(*nxt).second;
  now+=dis(t1,x)+dis(x,t2)-dis(t1,t2);
}
void del(int x){
  if(x==1)return;
  set<pair<int,int> >::iterator it=s.find(make_pair(dfn[x],x)),pre=it,nxt=it;
  if(it==s.begin())pre=--s.end();
  else pre--;
  if(it==--s.end())nxt=s.begin();
  else nxt++;
  int t1=(*pre).second,t2=(*nxt).second;
  now-=dis(t1,x)+dis(x,t2)-dis(t1,t2),s.erase(make_pair(dfn[x],x));
}
int calc(int gl,int gr){
  while(l>gl)add(a[--l]);
  while(r<gr)add(a[++r]);
  while(l<gl)del(a[l++]);
  while(r>gr)del(a[r--]);
  return now;
}
void solve(int l1,int r1,int l2,int r2){
  if(l2>r2)return;
  int mid=(l2+r2)>>1,pos=mid;
  for(int i=l1;i<=min(mid,r1);i++)if(f[i-1]+calc(i,mid)>g[mid])g[mid]=f[i-1]+calc(i,mid),pos=i;
  solve(l1,pos,l2,mid-1),solve(pos,r1,mid+1,r2);
}
int main(){
  s.insert(make_pair(1,1)),cin>>n>>k;
  for(int i=1,p;i<=n;i++)cin>>p,a[n-p+1]=i;
  for(int i=1,u,v;i<n;i++)cin>>u>>v,e[u].push_back(v),e[v].push_back(u);
  init(1,e);
  for(int i=1;i<=k;i++){
    solve(1,n,1,n);
    for(int j=1;j<=n;j++)f[j]=g[j],g[j]=0;
  }
  return cout<<f[n]<<'\n',0;
}