The lines \( L_1,L_2,\ldots,L_{20} \) are distinct. For \( n = 1, 2, 3, \ldots, 10 \) all the lines \( l_{2n-1} \) are parallel to each other and all the lines \( L_{2n} \) pass through a given \( P \). The maximum number of points of intersection of pairs of lines form the set \( \{L_1,L_2,\ldots,L_{20}\} \) is equal to \( \_\_\_\_\_\_\_\_\_\_ \).