foo.cc: In function 'int main()':
foo.cc:7:9: error: expected ',' or ';' before 'long'
    7 |         long long ret = 0;
      |         ^~~~
foo.cc:20:17: error: 'ret' was not declared in this scope
   20 |                 ret += a[i] * y;//的i次方;
      |                 ^~~
foo.cc:22:17: error: 'ret' was not declared in this scope
   22 |         cout << ret;
      |                 ^~~

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