#include <bits/stdc++.h>
using namespace std;
bool Check(int n, int m, int k) {
  int heights[n + 1], dynamo[n + 1];
  for (int i = 1; i <= n; ++i) cin >> heights[i];
  dynamo[0] = m;
  for (int i = 1; i < n; ++i) {
    dynamo[i] = dynamo[i - 1];
    if (heights[i] >= heights[i + 1] - k)
      dynamo[i] += min(heights[i], heights[i] - heights[i + 1] + k);
    else
      dynamo[i] += heights[i] - heights[i + 1] + k;
    if (dynamo[i] < 0) return false;
  }
  return true;
}
int main() {
  int t, n, m, k;
  cin >> t;
  while (t--) {
    cin >> n >> m >> k;
    if (Check(n, m, k))
      cout << "YES" << endl;
    else
      cout << "NO" << endl;
  }
  return 0;
}
