answer.code: In function ‘void prework()’:
answer.code:66:37: error: ‘gcd’ was not declared in this scope
   66 |                                 if (gcd (C[j].first, val) == tmp[len].first) tmp[len].second = C[j].second;
      |                                     ^~~
answer.code: In function ‘void calc()’:
answer.code:87:27: warning: structured bindings only available with ‘-std=c++17’ or ‘-std=gnu++17’ [-Wc++17-extensions]
   87 |                 for (auto [u, v] : o[i])
      |                           ^
answer.code:89:27: warning: structured bindings only available with ‘-std=c++17’ or ‘-std=gnu++17’ [-Wc++17-extensions]
   89 |                 for (auto [l, id] : q[i])
      |                           ^