foo.cc: In function ‘int main()’:
foo.cc:22:12: warning: ‘a’ may be used uninitialized [-Wmaybe-uninitialized]
   22 |         sum=a+d;
      |         ~~~^~~~
foo.cc:5:19: note: ‘a’ was declared here
    5 |         int y,m,d,a,sum;
      |                   ^