#include <bits/stdc++.h>
using namespace std;
#define F first
#define S second
#define pb push_back
#define int long long
#define no cout << "No" << '\n'
#define yes cout << "Yes" << '\n'
#define all(v) v.begin(), v.end()
#define rall(v) v.rbegin(), v.rend()
#define inp(v) for(auto &a : v) cin >> a;
#define out(v) for(auto &a : v) cout << a << ' ';
void solve(){
int n, k;
cin >> n >> k;
vector<int> v(n);
inp(v);
vector<int> vt[1005];
for(int i = 1; i <= n - 1; i++){
int x, y;
cin >> x >> y;
}
int ans = 0;
int sum = 0;
for(int i = 0; i < n; i++){
sum += v[i];
if(sum > k){
sum = v[i];
ans++;
}
}
cout << ans << '\n';
}
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
int t = 1;
//cin >> t;
while(t--) solve();
}
