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

