/in/foo.cc: In function 'int main()':
/in/foo.cc:6:15: warning: 'b' is used uninitialized in this function [-Wuninitialized]
  for(int i=1;i<=b;i++)
              ~^~~
/in/foo.cc:7:6: warning: 'a' may be used uninitialized in this function [-Wmaybe-uninitialized]
      for(int j=a;j<=b;j++)
      ^~~