/in/foo.cc: In function 'int main()':
/in/foo.cc:5:13: warning: variable 'set' set but not used [-Wunused-but-set-variable]
  int n,a[n],set=0,sum=0;
             ^~~
/in/foo.cc:5:11: warning: 'n' is used uninitialized in this function [-Wuninitialized]
  int n,a[n],set=0,sum=0;
           ^