B

#include <algorithm>
#include <cstdio>
#include <vector>
#include <cmath>

using namespace std;

struct point {
    long double x;
    long double y;

    long double len() {
        return sqrt(x * x + y * y);
    }
};

point operator-(point a, point b) {
    point res;

    res.x = a.x - b.x;
    res.y = a.y - b.y;

    return res;
}

long double height(point a, point b, point c) {
    point base = a - c;
    long double s = (b.x - a.x) * (c.y - a.y) - (b.y - a.y) * (c.x - a.x);

    if (base.len() == 0) {
        return 0;
    }

    return (abs(s) / base.len());
}

int main() {

    point p, a, b;
    long double x, y, z;

    scanf("%Lf %Lf %Lf %Lf %Lf %Lf", &p.x, &p.y, &a.x, &a.y, &b.x, &b.y);

    if (p.x == a.x && p.x == b.x) {
        if ((a.y < p.y && b.y > p.y) || (b.y < p.y && a.y > p.y)) {
            printf("0");
        } else {
            printf("%.5Lf", min(abs(p.y - a.y), abs(p.y - b.y)));
        }

        return 0;
    }

    if (p.y == a.y && p.y == b.y) {
        if ((a.x < p.x && b.x > p.x) || (b.x < p.x && a.x > p.x)) {
            printf("0");
        } else {
            printf("%.5Lf", min(abs(p.x - a.x), abs(p.x - b.x)));
        }

        return 0;
    }

    x = (p - b).len() * (p - b).len();
    y = (p - a).len() * (p - a).len();
    z = (a - b).len() * (a - b).len();

    if (x <= y + z && y <= x + z) {
        printf("%.5Lf", height(a, p, b));
    } else {
        printf("%.5Lf", sqrt(min(x, y)));
    }


    return 0;
}