View Compilation Error

0_0_28685956_32340.cpp: In function 'int main()':
0_0_28685956_32340.cpp:33:10: error: expected primary-expression before ',' token
   sort(a+,a+n,cmp);
          ^
0_0_28685956_32340.cpp:33:18: error: 'sort' was not declared in this scope
   sort(a+,a+n,cmp);
                  ^