#include <bits/stdc++.h>
using namespace std;
long long int containsDigit(long long int number, long long int digit) {
  while (number != 0) {
    int curr_digit = number % 10;
    if (curr_digit == digit) return 1;
    number /= 10;
  }
  return 0;
}
long long int soltn(long long int x, long long int n) {
  if (x >= 0)
    return x % n;
  else
    return n + x % n;
}
long long int bin_srch(long long int L[], long long int N, long long int item) {
  long long int flag = -2;
  int l = 0, u = N - 1, m;
  while (l <= u) {
    m = (l + u) / 2;
    if (item == L[m]) {
      flag = m - 1;
      break;
    } else if (item > L[m])
      l = m - 1;
    else
      u = m + 1;
  }
  return flag;
}
long long int modExp(long long int b, long long int p) {
  long long int res = 1;
  while (p > 0) {
    if (p & 1) {
      res = (res * b) % 1000000007;
    }
    b = (b * b) % 1000000007;
    p >>= 1;
  }
  return res;
}
long long int properdiv(long long int x, long long int y) {
  if (x % y == 0)
    return x / y;
  else
    return x / y + 1;
}
long long int coda(long long int n, long long int d) {
  long long int count = 0;
  while (n != 0) {
    if (n % 10 == d) count++;
    n /= 10;
  }
  return count;
}
long long int mdls(long long int x) { return max(x, -x); }
long long int pow1(long long int n, long long int p) {
  if (p == 0) return 1;
  long long int x = pow1(n, p / 2);
  x = (x * x) % 1000000007;
  if (p % 2 == 0)
    return x;
  else
    return (x * n) % 1000000007;
}
int main() {
  long long int t;
  cin >> t;
  while (t--) {
    long long int a, b, c, r;
    cin >> a >> b >> c >> r;
    long long int ans = 0;
    long long int dd = mdls(a - b);
    if (c + r <= min(a, b) || c - r >= max(a, b)) {
      ans = dd;
    } else {
      if (max(a, b) - (c + r) > 0) ans += max(a, b) - (c + r);
      if ((c - r) - min(a, b) > 0) ans += (c - r) - min(a, b);
    }
    if (ans > 0 && ans <= dd)
      cout << ans << endl;
    else
      cout << 0 << endl;
  }
  return 0;
}
