const int maxn=100010,mod=1e9+7,inf=0x3f3f3f3f;
int fa[maxn][25], dep[maxn],w[maxn];
int e[maxn],ne[maxn],m;
int h[maxn], idx = 0,n,root;
vector<int>num;
void add(int a,int b){
    e[idx]=b,ne[idx]=h[a],h[a]=idx++;
}
void init()
{
    memset(h, -1, sizeof h);
    idx = 0;
}
void bfs(int root)
{
    queue<int>q;
    memset(dep, 0x3f, sizeof dep);
    dep[0] = 0; 
    dep[root] = 1;
    q.push(root);
    while(!q.empty())
    {
        int t = q.front();
        q.pop();
        for(int i = h[t]; ~i; i = ne[i])
        {
            int j = e[i];
            if(dep[j] > dep[t] + 1)
            {
                dep[j] = dep[t] + 1;
                q.push(j);
                fa[j][0] = t; 
                for(int k = 1; k <= 15; k++)
                    fa[j][k] = fa[fa[j][k - 1]][k - 1];
                }
        }
    }
}
int lca(int a, int b)
{
    if(dep[a] < dep[b]) swap(a, b);
    for(int k = 15; k >= 0; k--)
         if(dep[fa[a][k]] >= dep[b]) a = fa[a][k]; 
    if(a == b) return a;
    for(int k = 15; k >= 0; k--)
        if(fa[a][k] != fa[b][k]) a = fa[a][k], b = fa[b][k];
    return fa[a][0];
}
int seq[maxn],top,first[maxn],las[maxn];
void dfs(int u,int fa){
  seq[++top]=u;
  first[u]=top;
  for(int i=h[u];~i;i=ne[i]){
    int j=e[i];
    if(j!=fa) dfs(j,u);
  }
  seq[++top]=u;
  las[u]=top;
}
struct node{
  int id,l,r,p;
}q[maxn];
int len,ans[maxn],res=0,st[maxn],cnt[maxn];
bool cmp(node a,node b){
  if(a.l/len==b.l/len) return a.r<b.r;
  return a.l/len<b.l/len;
}
void add(int x){
  //x=seq[x];
  st[x]^=1;
  if(st[x]==0){
    cnt[w[x]]--;
    if(!cnt[w[x]]) res--;
  }
  else{
    if(!cnt[w[x]]) res++;
    cnt[w[x]]++;
  }
}
void del(int x){
  x=seq[x];
  st[x]^=1;
  if(st[x]==0){
    cnt[w[x]]--;
    if(!cnt[w[x]]) res--;
  }
  else{
    if(!cnt[w[x]]) res++;
    cnt[w[x]]++;
  }
}
int main(){
  init();
  n=read,m=read;
  rep(i,1,n) w[i]=read,num.push_back(w[i]);
  sort(num.begin(),num.end());
  num.erase(unique(num.begin(),num.end()),num.end());
  rep(i,1,n)
    w[i]=lower_bound(num.begin(),num.end(),w[i])-num.begin();
  rep(i,1,n-1){
    int u=read,v=read;
    add(u,v);add(v,u);
  }
  dfs(1,-1);
  bfs(1);
  rep(i,1,m){
    int a=read,b=read;
    if(first[a]>first[b]) swap(a,b);
    int p=lca(a,b);
    if(a==p) q[i]={i,first[a],first[b]};
    else q[i]={i,las[a],first[b],p};
  }
  len=sqrt(top);
  sort(q+1,q+1+m,cmp);
  int nowl=1,nowr=0;
  rep(i,1,m){
    int id=q[i].id,ql=q[i].l,qr=q[i].r,p=q[i].p;
  //  cout<<id<<" "<<ql<<" "<<qr<<" "<<p<<endl;
    while(nowr<qr) add(seq[++nowr]);
    while(nowr>qr) add(seq[nowr--]);
    while(nowl<ql) add(seq[nowl++]);
    while(nowl>ql) add(seq[--nowl]);  
    if(p) add(p);
    ans[id]=res;
    if(p) add(p);
    //rep(i,1,n) cout<<cnt[i]<<" ";
    //puts("");
  }
  rep(i,1,m) cout<<ans[i]<<"\n";
  return 0;
}