/in/foo.cc: In function 'int main()':
/in/foo.cc:8:9: warning: 't' is used uninitialized in this function [-Wuninitialized]
  while(t!=0)
        ~^~~
/in/foo.cc:15:8: warning: 'a[0]' may be used uninitialized in this function [-Wmaybe-uninitialized]
  if(a[0]==2) sum=sum+2;
     ~~~^