
int main(int argc, char* argv[])
{
	int n;
	scanf("%d",&n);
	double *px,*py;
	px=(double *)malloc(sizeof(double) * n);
    py=(double *)malloc(sizeof(double) * n);
	int i;
	for(i=n-1;i>=0;i--)
	{
		scanf("%lf%lf",&px[i],&py[i]);
	}
    double dis;
    double mdis;
	mdis=0;
    int j;
	for(j=n-1;j>=0;j--)
	{
		for(i=j-1;i>=0;i--)
		{
			dis=(px[j]-px[i])*(px[j]-px[i])+(py[j]-py[i])*(py[j]-py[i]);
			if(mdis<=dis) mdis=dis;
		}
	}
	mdis=sqrt(mdis);
    free(px);
	free(py);
	printf("%.4f\n",mdis);
	return 0;
}
