#include <bits/stdc++.h>
using namespace std;
#define intf int_fast32_t
#define ll int_fast64_t
#define ull unsigned long long
#define int long long
#define endl '\n'
#define ye cout<<"YES"<<endl
#define no cout<<"NO"<<endl
#define F first
#define S second
#define pii pair<int,int>
const int MAX=1e5+5;
vector<int>vt[MAX];
void solve(){
int n,k;
cin>>n>>k;
int arr[n+1];
for(int i=1;i<=n;i++){
cin>>arr[i];
}
for(int i=1;i<=n;i++){
int x,y;
cin>>x>>y;
vt[y].push_back(x);
vt[x].push_back(y);
}
int say=0;
int cem=0;
for(int i=1;i<=n;i++){
if(cem+=arr[i]<=k){
cem+=arr[i];
}
else{
say++;
cem=arr[i];
}
}
cout<<say<<endl;
}
signed main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int t=1;
//cin>>t;
while(t--){
solve();
}
}
