/in/foo.cc: In function 'int main()':
/in/foo.cc:99:4: error: no match for 'operator[]' (operand types are 'Polynomial' and 'int')
   a[i] = (i & 1 == 1) ? mod - inv[i] : inv[i];
    ^
/in/foo.cc:99:17: warning: suggest parentheses around comparison in operand of '&' [-Wparentheses]
   a[i] = (i & 1 == 1) ? mod - inv[i] : inv[i];
               ~~^~~~
/in/foo.cc:100:4: error: no match for 'operator[]' (operand types are 'Polynomial' and 'int')
   b[i] = quick_pow(i, n, mod) * inv[i] % mod;
    ^
/in/foo.cc:102:8: error: cannot convert 'Polynomial' to 'll* {aka long long int*}' in assignment
  a.a = a;
        ^
/in/foo.cc:103:8: error: cannot convert 'Polynomial' to 'll* {aka long long int*}' in assignment
  b.a = b;
        ^