View Compilation Error

0_0_32325982_25413.cpp:4:9: error: expected unqualified-id before 'for'
         for(int i=n;i>=1;i--)
         ^
0_0_32325982_25413.cpp:4:21: error: 'i' does not name a type
         for(int i=n;i>=1;i--)
                     ^
0_0_32325982_25413.cpp:4:26: error: 'i' does not name a type
         for(int i=n;i>=1;i--)
                          ^
0_0_32325982_25413.cpp:19:15: error: expected constructor, destructor, or type conversion before '(' token
         printf("%d\n",output);
               ^