int main()
{   
	int n,j,k,l;
         double x0,y0,s=0,w;
	struct dian { double x,y;} *d;
	scanf("%d",&n);
	d=(struct dian *) malloc(sizeof(dian)*n);
	for(j=0;j<n;j++)
	{
		scanf("%lf%lf",&x0,&y0);
                  (d+j)->x=x0;
		(d+j)->y=y0;
	
	}
	for(l=0;l<n;l++)
	{
        for(k=l+1;k<n;k++)
		{
			w=((d+l)->x-(d+k)->x)*((d+l)->x-(d+k)->x)+((d+l)->y-                           (d+k)->y)*((d+l)->y-(d+k)->y);
			if(s<sqrt(w)){s=sqrt(w);}

		}
	}
	printf("%.4f",s);

	return 0;
}
