说明：  For example : There are 5 soldiers (A B C D E)with level numbers : 2 4 5 6 4; One method : C could teach B; B could teach A; So , A B C are eligible to study on the same broomstick. D could teach E;So D E are eligible to study on the same broomstick; Using this method , we need 2 broomsticks. Another method: D could teach A; So A D are eligible to study on the same broomstick. C could teach B; So B C are eligible to study on the same broomstick. E with no teacher or student are eligible to study on one broomstick. Using the method ,we need 3 broomsticks. ……
(Input file contains multiple test cases. In a test case,the first line contains a single positive number N indicating the number of soldiers.(0<=N<=3000) Next N lines :There is only one nonnegative integer on each line , indicating the level number for each soldier.( less than 30 digits); Output For each case, output the minimum number of broomsticks on a single line.)