import math
import sys
import itertools
import fractions
if __name__ == '__main__':
wtf = sys.stdin.read()
wtf = wtf.strip().split('\n')
T = int(wtf[0])
for t in wtf[1:]:
a,b,c,r = map(int,t.split())
d = c-r
e = c+r
A = min(a,b)
B = max(a,b)
a = A
b = B
ans = 0
if d >= a and d <= b:
ans += abs(d-a)
if e >= a and e <= b:
ans += abs(e-b)
if ans == 0:
if d <= a and e >= b:
ans = 0
else:
ans = abs(a-b)
print(ans)
#include<iostream>
using namespace std;
int main()
{
int t;
cin >> t;
while(t--)
{
int a, b, c, r;
cin >> a >> b >> c >> r;
int L = max(min(a, b), c - r);
int R = min(max(a, b), c + r);
cout << max(a, b) - min(a, b) - max(0, R - L) << endl;
}
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