foo.cc: In function ‘int main()’:
foo.cc:8:22: error: ‘a’ was not declared in this scope
    8 |                 cin>>a[i];
      |                      ^
foo.cc:11:20: error: ‘a’ was not declared in this scope
   11 |                 if(a[i]>=l&&a[i]<=r)cnt++;
      |                    ^