foo.cc: In function 'int main()':
foo.cc:18:6: error: 'a' was not declared in this scope
   18 | swap(a[n-1],a[n-2]);
      |      ^
foo.cc:23:2: error: expected '}' at end of input
   23 | }
      |  ^
foo.cc:7:11: note: to match this '{'
    7 | while(t--){
      |           ^
foo.cc:23:2: error: expected '}' at end of input
   23 | }
      |  ^
foo.cc:4:11: note: to match this '{'
    4 | int main(){
      |           ^