#include<bits/stdc++.h>
using namespace std;
#define int long long
#define double long double
#define endl '\n'
int n,m,a[200009],fa[200009][20],dep[200009],sz[200009],dfn[200009],dfnc,anti[200009];
int c[200009],d[200009];
set<pair<int,int> > s;
vector<int> g[200009];
void dfs(int u,int f){
	dep[u]=dep[f]+1;fa[u][0]=f;anti[dfn[u]=++dfnc]=u;sz[u]=1;
	for(int i=1;i<20;i++)fa[u][i]=fa[fa[u][i-1]][i-1];
	for(int v:g[u])if(v!=f)dfs(v,u),sz[u]+=sz[v];
}
struct fenwick{
	vector<int> ch;
	int sum[200009];
	void clear(){for(int x:ch)sum[x]=0;ch.clear();}
	void upd(int x,int f){while(x<=n)ch.push_back(x),sum[x]+=f,x+=x&-x;}
	int query(int x){int f=0;while(x)f+=sum[x],x-=x&-x;return f;}
	int query(int l,int r){return query(r)-query(l-1);}
}tr;
signed main(){
	ios::sync_with_stdio(0);
	cin.tie(0);cout.tie(0);
	cin>>n>>m;
	for(int i=1;i<=n;i++)cin>>a[i];
	for(int i=1;i<n;i++){
		int u,v;cin>>u>>v;
		g[u].push_back(v);
		g[v].push_back(u);
	}
	dfs(1,0);
	s.insert({1,n});
	while(--m){
		pair<int,pair<int,pair<int,int> > > ans={0,{0,{0,0}}};
		for(auto p:s){
			tr.clear();
			for(int i=p.first,cur=0;i<=p.second;i++){
				int u=a[i];
				if(tr.query(dfn[u],dfn[u]+sz[u]-1)){c[i]=(cur-1)*2;continue;}
				for(int p=15;~p;p--)
					if(fa[u][p]&&!tr.query(dfn[fa[u][p]],dfn[fa[u][p]]+sz[fa[u][p]]-1))
						u=fa[u][p];
				cur+=dep[a[i]]-dep[u]+1;
				tr.upd(dfn[a[i]],1);
				c[i]=(cur-1)*2;
			}
			tr.clear();
			for(int i=p.second,cur=0;i>=p.first;i--){
				int u=a[i];
				if(tr.query(dfn[u],dfn[u]+sz[u]-1)){d[i]=(cur-1)*2;continue;}
				for(int p=15;~p;p--)
					if(fa[u][p]&&!tr.query(dfn[fa[u][p]],dfn[fa[u][p]]+sz[fa[u][p]]-1))
						u=fa[u][p];
				cur+=dep[a[i]]-dep[u]+1;
				tr.upd(dfn[a[i]],1);
				d[i]=(cur-1)*2;
			}
			for(int i=p.first;i<p.second;i++)
				ans=max(ans,{c[i]+d[i+1]-c[p.second],{i,p}});
		}
		s.erase(ans.second.second);
		s.insert({ans.second.second.first,ans.second.first});
		s.insert({ans.second.first+1,ans.second.second.second});
	}
	int ans=0;
	for(auto p:s){
		tr.clear();
		for(int i=p.first,cur=0;i<=p.second;i++){
			int u=a[i];
			if(tr.query(dfn[u],dfn[u]+sz[u]-1)){c[i]=(cur-1)*2;continue;}
			for(int p=15;~p;p--)
				if(fa[u][p]&&!tr.query(dfn[fa[u][p]],dfn[fa[u][p]]+sz[fa[u][p]]-1))
					u=fa[u][p];
			cur+=dep[a[i]]-dep[u]+1;
			tr.upd(dfn[a[i]],1);
			c[i]=(cur-1)*2;
		}
		ans+=c[p.second];
	}
	cout<<ans<<endl;
	return 0;
}