#include<bits/stdc++.h>
using namespace std;

#define int long long
#define pb push_back
const int N=3e4+100,B=15,INF=1e9;
inline int chkmax(int &x,int y){ return y>x?x=y,1:0; }
#define rd read()
#define gc getchar() 
inline int read(){
	int x=0,f=0; char c=gc;
	for(;c<'0'||c>'9';c=gc) f|=(c=='-');
	for(;c>='0'&&c<='9';c=gc) x=(x<<1)+(x<<3)+(c^48);
	return f?-x:x;
}

int n,m,a[N];
vector<int> G[N];

int dfn[N],d_c=0,st[N][B+5],dep[N];
inline int get(int x,int y){ return dfn[x]<dfn[y]?x:y; }
void dfs0(int u,int fu){
	st[dfn[++d_c]=u][0]=fu,dep[u]=dep[fu]+1;
	for(int v:G[u]) if(v!=fu) dfs0(v,u);
}
inline void init(){ for(int k=1;k<=B;++k) for(int i=1;i+(1<<k)-1<=n;++i) st[i][k]=get(st[i][k-1],st[i+(1<<(k-1))][k-1]); }
inline int flca(int x,int y){ if(x==y) return x; if((x=dfn[x])>(y=dfn[y])) swap(x,y); int k=__lg(y-(++x)+1); return get(st[x][k],st[y+1-(1<<k)][k]); }
inline int fdis(int x,int y){ return dep[x]+dep[y]-2*dep[flca(x,y)]; }

int f[N][100],p[N][100];

int idx[N],i_c=0;
int sol(int l,int r){
	i_c=0; for(int i=l;i<=r;++i) idx[++i_c]=a[i]; idx[++i_c]=1;
	sort(idx+1,idx+i_c+1,[&](int x,int y){ return dfn[x]<dfn[y]; });
	int res=fdis(idx[i_c],idx[1]);
	for(int i=1;i<i_c;++i) res+=fdis(idx[i],idx[i+1]);
	return res;
}

signed main(){

	n=rd,m=rd;
	for(int i=1;i<=n;++i) a[i]=rd;
	for(int i=1,x,y;i<n;++i) x=rd,y=rd,G[x].pb(y),G[y].pb(x);
	
	dfs0(1,0),init();
	
	for(int i=0;i<=n;++i) for(int j=0;j<=m;++j) f[i][j]=-INF;
	f[0][0]=0;
	for(int i=1;i<=n;++i){
		for(int j=0;j<=m;++j){
			for(int k=0;k<i;++k){
				if(chkmax(f[i][j+1],f[k][j]+sol(k+1,i))) p[i][j+1]=k;
			}
		}
	}
	
	cout<<f[n][m]<<"\n";

	return 0;
}