import java.io.BufferedReader;
import java.io.InputStreamReader;
import static java.lang.Math.sqrt;
import static java.lang.Math.max;
public class mobile {
/**
* Checks if a given radius can cover all required points along the horizontal line of given length.
*
* @param radius the radius to check
* @param x the x-coordinates of the points
* @param y the y-coordinates of the points
* @param length the total length to cover
* @return true if the radius can cover the entire length, false otherwise
*/
private static boolean canCoverAll(double radius, int[] x, int[] y, int length) {
double endPoint = 0.0;
for (int i = 0; i < x.length; i++) {
if (y[i] > radius) {
continue; // If the y-coordinate is greater than the radius, coverage is impossible.
}
double delta = sqrt(radius * radius - y[i] * y[i]);
double right = x[i] + delta;
if (x[i] - delta <= endPoint) {
endPoint = max(endPoint, right);
}
}
return endPoint >= length;
}
/**
* Performs binary search to find the minimum radius required to cover the given length.
*
* @param x the x-coordinates of the points
* @param y the y-coordinates of the points
* @param length the total length to cover
* @return the minimum radius with a precision of 1e-3
*/
private static double findMinRadius(int[] x, int[] y, int length) {
double lo = 1.0, hi = 1.5e9, epsilon = 1e-3;
while (hi - lo > epsilon) {
double mid = lo + (hi - lo) / 2;
if (canCoverAll(mid, x, y, length)) {
hi = mid;
} else {
lo = mid;
}
}
return lo;
}
public static void main(String[] args) throws Exception {
try (BufferedReader reader = new BufferedReader(new InputStreamReader(System.in))) {
String[] input = reader.readLine().trim().split(" ");
int pairCount = Integer.parseInt(input[0]);
int length = Integer.parseInt(input[1]);
int[] x = new int[pairCount];
int[] y = new int[pairCount];
for (int i = 0; i < pairCount; i++) {
String[] position = reader.readLine().trim().split(" ");
x[i] = Integer.parseInt(position[0]);
y[i] = Integer.parseInt(position[1]);
}
double minRadius = findMinRadius(x, y, length);
System.out.printf("%.4f%n", minRadius);
}
}
}
