#include <iostream>
#include <cmath>
using namespace std;
 
double ras(double x1, double y1, double x2, double y2, double x3, double y3){
	double k,d;
	if(x1==x2){ //Если отрезок вертикальный - меняем местами координаты каждой точки.
	swap(x1, y1);
	swap(x2, y2);
	swap(x3, y3);
    }
    k=(y1-y2)/(x1-x2);//Ищем коэффициенты уравнения прямой, которому принадлежит данный отрезок.
    d=y1-k*x1;
	double xz=(x3*x2-x3*x1+y2*y3-y1*y3+y1*d-y2*d)/(k*y2-k*y1+x2-x1);
	double dl=-1;
	if((xz<=x2&&xz>=x1)||(xz<=x1&&xz>=x2)) dl=sqrt((x3-xz)*(x3-xz)+(y3-xz*k-d)*(y3-xz*k-d));//Проверим лежит ли основание высоты на отрезке.
	return dl;
}
int main() {
    double xa, xb, ya, yb, xc, xd, yc, yd, dl, dl1, dl2, dl3, dl4, min=-1,o,o1,o2,t=-2,s=-2;
    cin>>xa>>ya>>xb>>yb>>xc>>yc>>xd>>yd;
    o=(xb-xa)*(-yd+yc)-(yb-ya)*(-xd+xc);
    o1=(xb-xa)*(yc-ya)-(yb-ya)*(xc-xa);
    o2=(-yd+yc)*(xc-xa)-(-xd+xc)*(yc-ya);
    if(o!=0){
    	t=o1/o;
    	s=o2/o;
    }
    if((t>=0&&s>=0)&&(t<=1&&s<=1))min=0;//Проверим пересекаются ли отрезки.
    else{ 
        //Найдём наименьшую высоту опущенную из конца одного отрезка на другой.
        dl1=ras(xa,ya,xb,yb,xc,yc);
        min=dl1;
        dl2=ras(xa,ya,xb,yb,xd,yd);
        if((dl2<min&&dl2!=-1)||min==-1)min=dl2;
        dl3=ras(xc,yc,xd,yd,xa,ya);
        if((dl3<min&&dl3!=-1)||min==-1)min=dl3;
        dl4=ras(xc,yc,xd,yd,xb,yb);
        if((dl4<min&&dl4!=-1)||min==-1)min=dl4;
        if(min==-1){
            //В случае, если невозможно опустить высоту найдём минимальное расстояние между точками.
            dl1=sqrt((xa-xc)*(xa-xc)+(ya-yc)*(ya-yc));
            min=dl1;
            dl2=sqrt((xb-xd)*(xb-xd)+(yb-yd)*(yb-yd));
            if(dl2<min)min=dl2;
            dl3=sqrt((xb-xc)*(xb-xc)+(yb-yc)*(yb-yc));
            if(dl3<min)min=dl3;
            dl4=sqrt((xa-xd)*(xa-xd)+(ya-yd)*(ya-yd));
            if(dl4<min)min=dl4;
        }
    }
    cout<<min;
    return 0;
}

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