/in/foo.cc: In function 'int main()':
/in/foo.cc:36:26: warning: suggest parentheses around '-' inside '<<' [-Wparentheses]
         ans += f[i] * ((i-1 << 1) + 1);
                         ~^~

VJ4Error('ProblemDataNotFoundError', '题目 590c9c47d3d8a13210993bb0 的数据未找到。', 'newbzoj', '590c9c47d3d8a13210993bb0')