#include <bits/stdc++.h>
using namespace std;
signed main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  long long t;
  cin >> t;
  while (t--) {
    long long n, m, k;
    cin >> n >> m >> k;
    vector<long long> a(n, 0);
    for (long long i = 0; i < n; i++) cin >> a[i];
    for (long long i = 0; i < n - 1; i++) {
      if (a[i + 1] - k >= 0)
        m += (a[i] - a[i + 1] + k);
      else
        m += a[i];
      if (m < 0) {
        cout << "NO" << endl;
        break;
      }
    }
    if (m >= 0) {
      cout << "YES" << endl;
    }
  }
  return 0;
}
