foo.cc: In function 'int main()':
foo.cc:53:11: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   mid = l + r >> 1;
         ~~^~~
foo.cc:40:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d", &cake[i]);
   ~~~~~^~~~~~~~~~~~~~~~
foo.cc:44:36: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  for (int i = 1; i <= m; ++i) scanf("%d", &mouth[i]);
                               ~~~~~^~~~~~~~~~~~~~~~~