/in/foo.cc: In function 'int main()':
/in/foo.cc:19:18: warning: 'n' is used uninitialized [-Wuninitialized]
   19 |         int n,a[n],s=0;
      |                  ^
/in/foo.cc:19:13: note: 'n' declared here
   19 |         int n,a[n],s=0;
      |             ^