#include <bits/stdc++.h>
#define Hoshimachi signed
#define Suisei main
using namespace std;
#define int long long
#define tup tuple<int,int,int>
const int N=2e5+5,mod=1e9+7;
// nho reset
int n,t,a[N];
vector<int> adj[N];
int sz[N];
bool vis[N],ok[N],del[N];
void dfs_sz(int u, int par){
    sz[u]=1;
    vis[u]=1;
    for(auto v:adj[u]){
        if(v==par or !ok[v] or del[v]) continue;
        dfs_sz(v,u);
        sz[u]+=sz[v];
    }
}
void dfssum(int u, int par, int k, int &s){
    for(auto v:adj[u]){
        if(v==par or !ok[v]) continue;
        s+=sz[v]*(k-sz[v]);
        dfssum(v,u,k,s);
    }
}
void resetfull(){
    for(int i=1; i<=n; i++){
        sz[i]=0;
        vis[i]=ok[i]=del[i]=0;
    }
}
int Solve(int lim){
    resetfull();
    vector<int> st;
    for(int i=1; i<=n; i++){
        if(a[i]<=lim) ok[i]=1;
        else ok[i]=0;
    }
    vector<vector<int>> tplt;
    int ans=0;
    for(int i=1; i<=n; i++){
        if(ok[i] && !vis[i]){
            dfs_sz(i,0);
            int k=sz[i],s=0;
            dfssum(i,0,k,s);
            ans=(ans+(k-2)*s)%mod;
        }
    }
    return ans;
}
Hoshimachi Suisei(){
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    // freopen(".inp", "r", stdin);
    // freopen(".out", "w", stdout);
    cin>>n>>t;
    for(int i=1; i<=n; i++){
        cin>>a[i];
    }
    for(int i=1; i<n; i++){
        int u,v;
        cin>>u>>v;
        adj[u].push_back(v);
        adj[v].push_back(u);
    }
    cout<<(Solve(t)-Solve(t-1)+mod)%mod;
}