100168 G

#include <cstdio>
#include <cmath>

#define FILE_NAME "distance2"

using namespace std;

int main()
{
#ifdef ONLINE_JUDGE
    freopen(FILE_NAME".in", "r", stdin);
    freopen(FILE_NAME".out", "w", stdout);
#endif

    double x, y, x1, y1, x2, y2;
    scanf("%lf%lf%lf%lf%lf%lf", &x, &y, &x1, &y1, &x2, &y2);

    double a = y1 - y2, b = x2 - x1, c = x1 * y2 - y1 * x2;
    double k = abs((a * x + b * y + c) / sqrt(a * a + b * b));

    printf("%.12lf\n", k);

    return 0;
}