#include <bits/stdc++.h>
using namespace std;
#define endl '\n'
#define all(v) v.begin(),v.end()
#define rall(v) v.rbegin(),v.rend()
#define F first
#define S second
#define pf push_front
#define pb push_back
#define ll long long
#define ull unsigned long long
#define ld long double
#define int long long
#define vi vector <int>
#define pii pair <int,int>
#define yes cout << "YES" << endl
#define no cout << "NO" << endl
#define out(v) for (auto x:v) cout << x << endl
const int MAX=100005;
const int MOD=1e9+7;
//vector<int> vt[MAX];
//int vis[100000+5];
//void bfs(int a){
// queue<int> q;
// q.push(a);
// vis[a] = 1;
// while (!q.empty()) {
// int u=q.front();
// q.pop();
// for (int v : vt[u]) {
// if (!vis[v]) {
// vis[v]=1;
// q.push(v);
// }
// }
// }
//}
signed main(){
int n,k;
cin>>n>>k;
vi vt(n);
for(int i=0;i<n;i++){
cin>>vt[i];
}
int m=n-1;
while(m--){
int a,b;
cin>>a>>b;
}
int ans=0;
int sum=0;
for(int i=0;i<n;i++){
sum+=vt[i];
if(sum>=k+1){
ans++;
sum=vt[i];
}
}
cout<<ans;
}
