#include <iostream>
#include <cstdio>
#include <set> 
using namespace std;
int n,m,p[200005];
int u[400005],v[400005],first[200005],nxt[400005];
int f[2005][2005];
int fa[200005],depth[200005],sz[200005],son[200005];
int top[200005],idx,dfn[200005],nfd[200005];
void dfs1(int now,int f,int d){
	fa[now]=f,depth[now]=d;
	sz[now]=1;
	for (int i=first[now];i;i=nxt[i])
		if (v[i]!=f){
			dfs1(v[i],now,d+1);
			sz[now]+=sz[v[i]];
			if (son[now]==0||sz[v[i]]>sz[son[now]])son[now]=v[i];
		}
	return;
}
void dfs2(int now,int f,int t){
	top[now]=t;
	++idx;
	dfn[now]=idx,nfd[idx]=now;
	if (son[now]!=0)dfs2(son[now],now,t);
	for (int i=first[now];i;i=nxt[i])
		if (v[i]!=f&&v[i]!=son[now])dfs2(v[i],now,v[i]);
	return; 
}
int lca(int a,int b){
	if (a==0||b==0)return 0;
	while(top[a]!=top[b]){
		if (depth[top[a]]<depth[top[b]])swap(a,b);
		a=fa[top[a]];
	}
	if (depth[a]>depth[b])return b;
	return a;
}
int dis(int a,int b){
	return depth[a]+depth[b]-2*depth[lca(a,b)];
}
namespace DS{
	set<int> c;
	int sum;
	void init(){
		c.clear();
		c.insert(0),c.insert(n+1);
		sum=0;
		return;
	}
	void ins(int x){
		int l,r;
		set<int>::iterator it=c.lower_bound(x);
		r=(*it);
		it--;
		l=(*it);
		sum-=dis(nfd[l],nfd[r]);
		sum+=dis(nfd[l],x);
		sum+=dis(x,nfd[r]);
		c.insert(dfn[x]);
		return;
	}
	void del(int x){
		c.erase(x);
		int l,r;
		set<int>::iterator it=c.lower_bound(x);
		r=(*it);
		it--;
		l=(*it);
		sum+=dis(nfd[l],nfd[r]);
		sum-=dis(nfd[l],x);
		sum-=dis(x,nfd[r]);
		return;
	}
}
int main(){
	scanf("%d%d",&n,&m);
	for (int i=1;i<=n;i++)scanf("%d",&p[i]);
	for (int i=1;i<n;i++){
		scanf("%d%d",&u[i],&v[i]);
		nxt[i]=first[u[i]],first[u[i]]=i;
		u[i+n]=v[i],v[i+n]=u[i];
		nxt[i+n]=first[u[i+n]],first[u[i+n]]=i+n; 
	}
	dfs1(1,0,0);
	dfs2(1,0,1);
	for (int i=1;i<=n;i++){
		DS::init();
		for (int j=i;j>=1;j--){
			DS::ins(p[j]);
			for (int k=1;k<=m;k++)
				f[i][k]=max(f[i][k],f[j-1][k-1]+DS::sum);
		}
	}
	cout<<f[n][m]<<endl;
	return 0;
}