double length(double x1,double y1,double x2,double y2)
{
	return sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
}
void main()
{
	double length(double,double,double,double);
	double num[100][2],max,temp;
	int n,i,j;
	scanf("%d",&n);
	for(i=0;i<n;i++)
		scanf("%lf%lf",&num[i][0],&num[i][1]);
	max=length(num[0][0],num[1][0],num[0][1],num[1][1]);
	for(i=0;i<n;i++)
		for(j=i+1;j<n;j++)
		{
			if(max<(temp=length(num[i][0],num[i][1],num[j][0],num[j][1])))max=temp;
		}
		printf("%.4f\n",max);
}