/in/foo.cc: In function 'int main()':
/in/foo.cc:17:8: warning: statement has no effect [-Wunused-value]
  for (i; i < 32; ++i)
        ^
/in/foo.cc:19:31: error: 'pow' was not declared in this scope
   result += a[i] * pow(2, i-16);
                               ^
/in/foo.cc:23:33: error: 'pow' was not declared in this scope
   result += a[i] * pow(2, i + 16);
                                 ^