View Compilation Error

0_0_37716402_28290.cpp: In function 'void solve()':
0_0_37716402_28290.cpp:52:14: error: expected unqualified-id before '[' token
         auto [u, v, w] = arr[i];
              ^
0_0_37716402_28290.cpp:53:17: error: 'w' was not declared in this scope
         if (vis[w]) continue;
                 ^
0_0_37716402_28290.cpp:54:19: error: 'u' was not declared in this scope
         ans += (p[u] ^ p[v]).count();
                   ^
0_0_37716402_28290.cpp:54:26: error: 'v' was not declared in this scope
         ans += (p[u] ^ p[v]).count();
                          ^