/in/foo.cc: In function 'int main()':
/in/foo.cc:143:18: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17' [-Wc++17-extensions]
  143 |             auto [p_u, p_d] = prev.states[ps];
      |                  ^
/in/foo.cc:147:22: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17' [-Wc++17-extensions]
  147 |                 auto [c_u, c_d] = cur.states[cs];
      |                      ^