foo.cc: In function ‘void dijkstra(int)’:
foo.cc:38:15: warning: structured bindings only available with ‘-std=c++17’ or ‘-std=gnu++17’ [-Wc++17-extensions]
   38 |     for (auto [v, id, add] : adj[u]){
      |               ^
foo.cc: In function ‘void build()’:
foo.cc:57:15: warning: structured bindings only available with ‘-std=c++17’ or ‘-std=gnu++17’ [-Wc++17-extensions]
   57 |     for (auto [v, id, w] : adj[u]){
      |               ^
foo.cc: In function ‘void tarjan(int, int)’:
foo.cc:72:13: warning: structured bindings only available with ‘-std=c++17’ or ‘-std=gnu++17’ [-Wc++17-extensions]
   72 |   for (auto [v, id, ff] : sp_adj[u]){
      |             ^