#include <bits/stdc++.h>
using namespace std;
long long max(long long a, long long b) {
  if (a > b) return a;
  return b;
}
long long min(long long a, long long b) {
  if (a > b) return b;
  return a;
}
int main() {
  {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
  };
  int q;
  cin >> q;
  while (q--) {
    long long a, b, c, r;
    cin >> a >> b >> c >> r;
    long long ans = 0;
    if (b < a) {
      long long temp = b;
      b = a;
      a = temp;
    }
    long long low = c - r;
    long long high = c + r;
    if (a <= low && high <= b) {
      ans = b - a - (high - low);
    } else if (low <= a && high <= b && a <= high) {
      ans = b - a - (high - a);
    } else if (b <= high && a <= low && low <= b) {
      ans = b - a - (b - low);
    } else if (low <= a && b <= high) {
      ans = 0;
    } else {
      ans = b - a;
    }
    cout << ans << "\n";
  }
  return 0;
}
