int main( )      //?????
{      //?????
	int i,j,n;      //????
	double max_dis=0;    //????????
	double a[100][2],dis[100][100];    //??????
	cin >>n;      //????
	for(i=1;i<=n;i++)      //?????????
		cin >>a[i][0] >>a[i][1];
	for(i=1;i<=n;i++)      //???????????
		for(j=i+1;j<=n;j++)
			dis[i][j]=sqrt((a[i][0]-a[j][0])*(a[i][0]-a[j][0])+(a[i][1]-a[j][1])*(a[i][1]-a[j][1]));
	for(i=1;i<=n;i++)      //???????????
		for(j=i+1;j<=n;j++)
			if(dis[i][j]>max_dis) {max_dis=dis[i][j];}
	printf("%.4f\n", max_dis);      // ?????????????4?
    return 0;      //???????????????????
}      //????