#include <iostream>
#include <vector>
#include <cmath>
#include <algorithm>

using namespace std;

typedef long long ll;
typedef pair<ll,ll> PII;
const ll N = 1e5 + 10;
PII dp[N][30];
ll depth[N];
ll c[N];//零食 
struct node{
    vector<ll> childs;
}a[N];

ll n,m;

void dfs(ll i,ll fi){
    depth[i]=depth[fi]+1;
    dp[i][0]=(PII){fi,(1<<c[i])|(1<<c[fi])};
    for (ll j = 1;j <= 24;j ++){
        PII k1 = dp[i][j-1];
        PII k2 = dp[k1.first][j-1];
        dp[i][j] = (PII){k2.first,k1.second | k2.second};
    }
    for (auto t : a[i].childs){
        if (t == fi) continue;
        dfs(t,i);
    }
}
ll lca(ll x,ll y){
    if (depth[x] < depth[y]) swap(x,y);
    ll ans = (1<<c[x])|(1<<c[y]);
    for (ll i = 24;i >= 0;i --){
        PII k1 = dp[x][i];
        if (depth[k1.first] < depth[y]) continue;
        x = k1.first;
        ans |= k1.second;
    }
    if (x == y) return ans;
    for (ll i = 24;i >= 0;i --){
        PII k1 = dp[x][i];
        PII k2 = dp[y][i];
        if (k1.first == k2.first) continue;
        x = k1.first;
        y = k2.first;
        ans |= k1.second;
        ans |= k2.second;   
    }
    ans |= dp[x][0].second;
    ans |= dp[y][0].second;
    return ans;
}
ll lowbit(ll x){
    return x&-x;
}
int main(){
    cin >> n >> m;
    for (ll i = 1;i <= n;i ++){
        cin >> c[i];
        c[i] --;
    }
    for (ll i = 1;i < n;i ++){
        ll x,y;cin >> x >> y;
        a[x].childs.push_back(y);
        a[y].childs.push_back(x);
    }
    c[0] = c[1];
    dfs(1,0);
    while (m --){
        ll x,y;cin >> x >> y;
        ll t = lca(x,y);
        ll ans = 0;
        for (int i = 0;i <= 19;i ++){
            if (t & (1<<i))
                ans ++;
        }
        cout << ans << endl;
    }
    return 0;   
}