public void Solve(TextReader input, TextWriter output)
{
var scanner = new StreamTokenizer(input);
int testNum = scanner.NextInt();
Random rnd = new Random();
foreach (int caseId in Enumerable.Range(1, testNum))
{
int n = scanner.NextInt();
double d = scanner.NextDouble();
double[] p = new double[n];
int[] v = new int[n];
for (int i = 0; i < n; i++)
{
p[i] = scanner.NextDouble();
v[i] = scanner.NextInt();
}
double left = 0, right = 1E12;
while (right - left > 1E-8)
{
double mid = (left + right) / 2;
bool success = true;
double bound = -1E10;
for (int i = 0; i < n; i++)
{
if (v[i] > 0)
{
bound = Math.Max(p[i] - mid, bound);
bound += d * v[i];
if (bound - d > p[i] + mid)
{
success = false;
break;
}
}
}
if (success)
{
right = mid;
}
else
{
left = mid;
}
}
output.WriteLine("Case #{0}: {1}", caseId, left);
}
output.Close();
}
