int main(int argc, char* argv[])
{
	int n,i,j;
	scanf("%d",&n);
	float *a;
	float *b;
	double max=0.0000,length;
	a=(float*)malloc(sizeof(float)*n);
	b=(float*)malloc(sizeof(float)*n);
	for(i=0;i<n;i++){
		scanf("%f%f",&a[i],&b[i]);
	}
    for(i=0;i<n;i++)
		for(j=0;j<n;j++){
			length=(double)sqrt((a[i]-a[j])*(a[i]-a[j])+(b[i]-b[j])*(b[i]-b[j]));
			if(length>max)
				max=length;
		}
	
	printf("%.4lf",max);
    return 0;
}

