/in/foo.cc: In function 'int main()':
/in/foo.cc:18:7: warning: variable 'a' set but not used [-Wunused-but-set-variable]
  long a, n, cnt = 0;
       ^
/in/foo.cc:27:22: warning: 'sum[0]' may be used uninitialized in this function [-Wmaybe-uninitialized]
  long max = n + sum[0];
                 ~~~~~^