foo.cc: In function ‘int main()’:
foo.cc:9:18: warning: ‘s’ may be used uninitialized [-Wmaybe-uninitialized]
    9 |                 s+=n%10;
      |                 ~^~~~~~
foo.cc:5:15: note: ‘s’ was declared here
    5 |         int n,s;
      |               ^