int main(int argc, char* argv[])
{
	struct point{
		double x,y;
	}dian[1000];
	int n,i,j;
	double mdis=0,dis;
	scanf("%d",&n);
	for(i=0;i<n;i++)
		scanf("%lf %lf",&dian[i].x,&dian[i].y);
    for(i=0;i<(n-1);i++)
	{
		for(j=i+1;j<n;j++)
		{
			dis=(double)sqrt((dian[i].x-dian[j].x)*(dian[i].x-dian[j].x)+(dian[i].y-dian[j].y)*(dian[i].y-dian[j].y));
			
	        if(mdis<dis)
		    mdis=dis;
		}
	}
	printf("%.4lf\n",mdis);
	return 0;
}

