

int main() 
{
	int n, i, j;
	double x[1000], y[1000], ll[1000][1000]={{0},{0}}, l[1000]={0}, dis=0;
	scanf( "%d", &n );
	for( i=0; i<n; i++ ) {
		scanf( "%lf %lf", &x[i], &y[i] );
	}
	for( i=0; i<n; i++ )
	{
		for( j=0; j<n; j++ ) 
		{
			ll[i][j] = sqrt( (x[i]-x[j])*(x[i]-x[j]) + (y[i]-y[j])*(y[i]-y[j]) );
		   if( ll[i][j] > dis )
		   {
			dis = ll[i][j];
		   }
		}
	}
	printf("%.4f\n", dis);
	return(0);
} 
